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MAGAZINE 



06.2011 



VOL 9 NO. 6 



Did you know that each article in SERVO Magazine has its own 
webpage? It's where you go for downloads, comments, updates, 
corrections, or to link to the article in the digital issue. The unique 
link for each webpage Is included with the article. 




PAGE 70 



V> 




08 Robytes 

by Jeff Eckert 
Stimulating Robot Tidbits 

10 GeerHead 

by David Geer 
A Robot's Touch 

14 Ask Mr. Roboto 

by Dennis Clark 

Your Problems Solved Here 



Departments 

06 Mind/ Iron 
18 Events Calendar 
New Products 

21 Showcase 

22 Bots in Brief 

67 SERVO Webstore 
Robo-Links 
Advertiser's Index 





PAGE 22 


t 


R9 


Q 


-V/' 


-TV- 11 





62 The NXT Big Thing #9 

by Greg Intermaggio 
In Control! 

70 Twin Tweaks 

by Bryce and Evan Woolley 

Why Did The Robot Cross The Road? 

70 Then and Now 

by Tom Carroll 

New Approaches to Robotics Education 



The Combat Zone... 

features 

26 BUILD REPORT: 

Moras — A 30 lb Angled Bar Spinner 

28 POTPOURRI 3.0 
32 The Reality of TV 



Events 

32 Completed and Scheduled 
Events 




SERVO MtfgGZJne (ISSN 1 546-QS92/CDN Pub Agree#40702530) is published monthly for $24.95 per year byT & L Publications, Inc., 430 Prince I and Court, Corona, CA 92879. 
PERIODICALS POSTAGE PAID AT CORONA. CA AND AT ADDITIONAL ENTRY MAILING OFFICES, POSTMASTER: Send address changes to SERVO Magazine, P.O. Box 
1 5277, North Hollywood, C A 9 1 6 1 1 or Station A, RO. Box 54>Windsor ON N9A 6J5; tpcreturns@servomagazine,com 



4 SERVO 06,2011 



In This Issue ... 




36 A uart/spi Monitor 
lor Your Micro — Part 2 

by Mark Mitchell 

This month, we'll finish off the tool that lets us 
"peek under the hood" of our controller and 
then we'll put it into a useable housing. 

42 Building Bots From Found Parts 

by Gordon McComb 

There's virtually no limit to the number and 
type of items you can use in your robot 
projects. Find out just how easy it is to build 
your own "no-cut" robot out of ready-made 
parts available at your local hardware store. 

49 CPLDs — Part 4: 
HDL Programming 

by David Ward 

Now that you have a better idea of what a 
CPLD is and what it can do f it's time to 
introduce and begin using HDL (hardware 
description language). 



54 Make Your Robot's Wires Extinct 

by Fred Eady 

Find out about a new 8051 -based powerhouse 
that will allow you to lose the wire connection 
to the microcontroller in your robot, 



Programming the LEGO NXT: 
An Alternative Approach 
Suitable For Developing 
Tomorrow's Engineers 

by John Blankenshlp and Samuel Mishal 
LEGO makes building robots easier, and now 
programming a LEGO NXT can be just as easy. 
Learn about the open-source LegoLibrary.bas. 





SERVO 06.2011 5 





Mind / Iron 



by Bryan Bergeron, Editor M 



Embedded Linux 
Development Platform 

I had the pleasure of speaking with a fellow robotics 
enthusiast Eric Gregori, about his latest contribution to 
the field of affordable robotics. Eric started building 
robots at eight, and continues his passion/obsession 
today as the Embedded Firmware Product Specialist at 
Freescale Semiconductors. Because Freescale is into 
selling silicon and Eric is into robotics, it seems as though 
he's one of the lucky few people that get paid for what 
they would otherwise do for free. 

Eric's latest project is extending his RobotSee 
software platform (www-EMGRobotics.com) to work 
with the new robot from Freescale: the Freescale Tower 
Mechatronic Robot. RobotSee is a free, open source 
robotics toolkit that works with Windows, the Chumby, 
Android tablets, and phones, and Linux. As you might 
expect, RobotSee provides a vision toolkit that includes 
features such as face recognition. Moreover, the toolkit — 
which uses an easy-to-use language with similarities to 
both C and Basic - supports voice recognition, speech 
synthesis, GPS navigation, and even an interface to those 
affordable brain-machine interfaces that are on the 
market. 

The Freescale Tower Mechatronic Robot (which I'll 




refer to as simply 'Mech') is Freescale's first entry in the 
market targeting robotics enthusiasts. At $199, Freescale 
is positioning the robot as the next step up from robots 
based on the Stamp or Arduino. The basic board — 
which goes for $99 - uses a MC52259 32-bit 
microcontroller with 64K RAM and 51 2K Flash, It has 
space for two plug-in daughter boards, including a $25 
magnetometer or compass and a $99 three-axis 
accelerometer. There's also a pair of USB connectors, 
analog and digital I/O, PC, SPI, and even a legacy RS-232 
port. Development software includes free versions of 
CodeWarrior and RobotSee. In terms of difficulty, 
RobotSee is just a bit more challenging than, say, 
programming the BASIC Stamp. CodeWarrior, on the 
other hand, requires modest familiarity with C/C++ 
programming, and doesn't come with built-in libraries for 
vision, speech, voice, and the rest. 

Where Mech becomes interesting is when you drop 
in the 3" x 3" 1 GHz/1 GB Linux board on top of the 
basic board. The $149 board has enough power to 
support, say, your own robot swarm. You can add a 
webcam for vision recognition, a WiFr or XBee 
transceiver for wireless communications, or your own 
custom sensors. As you can see, you'll want to perform a 
brain transplant as soon as you wrap your head around 

the Linux board. 
min i miimmn Perhaps a crawler or 

R/C truck body would 
be more appropriate for 
the horsepower the 
Linux board brings to 
the table. Several years 
ago, I was forced to 
upgrade my hardware 
from lowly 
microcontrollers to a 
real time Linux board, at 
a cost of over $1,000 
for the bare board. At 
$149, the Linux board is 
a bargain if you want to 
get into real time path 
finding or data fusion. If 
you already have a 
robot platform and 
know what you want to 



6 SERVO 06.2011 




Published Monthly By 

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ASSOCIATE PUBLISHER/ 
VP OF SALES/MARKETING 

Robin Lemieux 
display@servomagazine.com 

EDITOR 

Bryan Bergeron 
techedit-servo@yahoo.com 

CONTRIBUTING EDITORS 

Jeff Eckert Jenn Eckert 

Tom Carroll David Geer 

Dennis Clark R. Steven Rainwater 

Fred Eady Kevin Berry 

Bryce Wool ley EvanWoolley 

Gregory Intermaggio Gordon McComb 
David Ward Mark Mitchell 

John Blankenship Samuel Mishal 
Mike Jeffries Pete Smith 

CIRCULATION DIRECTOR 

Tracy Kerley 
subscribe@servomagazine.com 

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Copyright 201 I by 
T & L Publications, Inc. 

All Rights Reserved 

All advertising is subject to publisher's approval. 
We are not responsible for mistakes, misprints, 
or typographical errors, SERVO Magazine assumes 
no responsibility for the availability or condition of 
advertised items or for the honesty of the 
advertiser. The publisher makes no claims for the 
legality of any item advertised in SEflVO.This is the 
sole responsibility of the advertiser. Advertisers and 
their agencies agree to indemnify and protect the 
publisher from any and all claims, action, or expense 
arising from advertising placed in SERVO. Please 
send all editorial correspondence, UPS, overnight 
mail, and artwork to: 430 Princeland Court, 
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Printed in the USA on SFI Si FSC stock. ^SSSSST ^ 






do with more capable hardware, I'd simply go for the two boards. On the 
other hand, if you're looking for an experimentation platform, then the Mech 
is worth considering. It has a dozen touch pads and does cradle the board(s) 
nicely. The LED eyes, nose, and mouth don't do anything for me, but again, 
it's handy to have LEDs already wired in circuit for testing purposes. 

Whatever your robot platform, check out the RobotSee site. And, if you 
need more computational capacity, consider the fully configured Mech. 




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El-ll-ITV+l 




Bird Flight iphered 

In 2009, we introduced you to 
some flying penguins from Festo AG 
(www.festo.com), and last February, 
they came up with a handling 
assistant inspired by an elephant's 
trunk. This time, the company's 
fascination with animatronics has 
manifested itself in the form of 
SmartBird, an amazingly lifelike 
version of the herring gull. According to the company, 
'With SmartBird, Festo has succeeded in deciphering the 
flight of birds — one of the oldest dreams of humankind. 11 
The bird can start, fly, and land autonomously with no 
drive mechanism other than its wings. Maneuverability is 
enhanced by wings that twist at specific angles, as well as 
flapping up and down - a trick made possible by the 



ult eyes Festo 's SmartBird 
with suspicion. 



by Jeff and Jenn Eckert 




"active articulated torsional drive unit," 
The tail generates lift as well, in 
addition to its standard functions of 
elevator and rudder. In terms of the 
nuts and bolts of the thing, it is driven 
by a lithium polymer battery (two 
cells, 7.4V, 450 mA), a Graupner 
Compact 135 brushless motor, and a 
Texas Instruments MCU LM3S81 1 
microcontroller. It's a bit larger than 
the real thing, with a wingspan of 2 m (78.7 in) and a 
torso length of 1 .07 m (42 in), vs, an approx. 56 in 
wingspan and 25 in body. It weighs significantly less, 
however: 0.45 kg/15.9 oz vs. up to 1.5 kg/3.3 lb. For 
more details, just point your browser to www.jkeckert. 
com/freedownloads/SmartBird.pdf and download the 
eight page brochure. 



But System To Test Chemicals 

It isn't news that robots are taking over more and more tasks that are 
dangerous or downright repugnant to humans, but the National Institutes of 
Health's Chemical Genomics Center (www.genome.gov) has given their 
machines a highly ambitious assignment. Its Tox21 program — undertaken in 
collaboration with several other agencies — will use a robot system to test 
10,000 chemicals for toxicity. The results should provide information about which 
of these substances have the potential to lead to adverse health effects. The 
chemical under analysis will include a variety of compounds found in industrial 
and consumer products, food additives, and pharmaceuticals. And this could be 
only the beginning, as the list of suspect substances was referred to as the 
"initial" selection. 

Tox21 has already tested more than 2,500 chemicals using various technologies, but the new system will speed up the 
process. As NCGC Director Christopher Austin noted, "The Tox21 collaboration will transform our understanding of 
toxicology with the ability to test in a day what would take one year for a person to do by hand." 




A robot arm retrieves assay plates from 
incubators. (Credit: Maggie Bartlett, NjGRt.) 



Drug-Dealing lutomaton 

Assuming the Tox21 program confirms that your favorite medication 
is acceptable, robotics may play an additional role in making sure you 
get the right prescription. A new pharmacy at the University of 
California, San Francisco (UCSF) Medical Center (www.ucsfhealth.org) 
is using robotic technology and electronics to prepare and track 
medications, thereby improving patient safety. Customers may not be 
aware of the bot's activities, as they are housed in a secure, sterile 
environment, but they are busy preparing oral and injectable 
medications, including toxic chemotherapy drugs. According to Mary 
Anne Koda-Kimble, dean of the UCSF School of Pharmacy, "Automated 
medication dispensing frees pharmacists from the mechanical aspects of 
the practice. This technology, with others, will allow pharmacists to use their pharmaceutical care expertise to assure that 
patients are treated with medicines tailored to their individual needs." Reportedly, not a single error has occurred in the 
350,000 doses prepared during the system's phase-in. 




Robotic pill picker and plastic bags for 
medications. (Credit: Susan MerreltlUCSF.} 



8 SERVO 06.2011 



www.servomagazine.com/index.php7/magazine/article/june2011_Robytes 



Something In Your Eye? 

Lest we close out this month's offerings without providing something to 
raise goose bumps on the squeamish, consider a microbot developed at the 
Swiss-based Institute of Robotics and Intelligent Systems (IRIS, 
wwwJris.ethz.ch). It's the latest in an effort to create tiny machines that can 
be injected into your eyeball and used to treat such conditions as macular 
degeneration. The electromagnetically controlled devices can move to a target 
location and remain there for months, releasing drugs. The bots can also install 
a biodegradable drug capsule and then be removed with a magnetic needle. If 
you haven't squirmed enough, visit http://bcove.me/bb27w039 for a video of 
the bot creeping around inside the eye of a dead pig, 




Microbot sitting on a vein in a chicken 
embryo, used as a model for retinal veins, 

(Credit: IRIS.) 



Reconfigurable Bot Goes Commercial 

With funding from the National Science Foundation, a reconfigurable 
modular robot invented at the University of California, Davis (www.ucdavis.edu) 
is headed for commercial development. The iMobot, developed by Graham 
Ryland and Harry Cheng, is particularly useful as a teaching tool, and they say 
there are currently no commercially available research-grade robots. It also has 
potential applications for prototyping complex assemblies, and they speculate 
that it could eventually be 
configured for search-and-rescue 
operations. 

Each module has four degrees 
of freedom, with two joints in the 
center and a wheel on each end. It 
can roll on its wheels, crawl like an 
inchworm, or raise one end of its 
body and pan around (as, e.g., a 
camera platform). Individual 
modules can be combined into 
larger assemblies such as snakelike 
robots or larger, wheeled machines 
that can roll over smooth terrain. 

By using an off-the-shelf bot 
like iMobot, it is believed that 
researchers can work in such areas 
as Al, robot collaboration, and 
reconfigurable and adaptive 
systems without having to develop 
proprietary hardware systems. 

The new company, Barobo Inc. 
(www.barobo.com), received an 
initial grant of $150,000 for a six 
month period, with an additional 
$500,000 potentially available, The 
bot should be on the market by the 
end of the year. For a vid, go to 
YouTube and search ilvlobot SV 




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SERVO 06.2011 9 



5 LnJ 



by David Geer 



Contact the author at geercom@windstream.net 



A Robot's Touch 



He may not be the 
lead singer from 
Def Leppard, but he 
still "wants to touch 
you." Cody - a 
nurse assistant 
caregiver robot 
— wipes down 
subject's forearms 
to clean them, or 
touches them to 
offer comfort in a 
critical experiment 
with a surprising 
conclusion. 




The research is motivated by a pervasive nursing 
shortage globally which — according to the researchers 
Tiffany Chen, ChirvHung King, Charles Kemp, and Andrea 
Thorn az - is forecasted to increase in coming years. It 
should be noted that due to advances in health care that 
are increasing longevity, plus the retirement of the large 
baby boomer population, there will be a larger patient 
population requiring nursing care. 

Because bathing patients takes up a significant amount 
of a nurse's work day, teaching a robot to perform the task 
would free up a great deal of time for more critical services 
to patients. This experiment gave the roboticists insight on 
the type of touch people appreciate more when it comes 
from a robot. If the robot is touching them to provide a 
service (dean the forearm), the touch is welcomed. If the 
touch is to transfer comfort, the subjects do not appreciate 
it as much, This parallels research conducted on human 
nurse and patient touch. The researchers also examined 
whether a warning as to the purpose of the touch 
beforehand was helpful. 

10 SERVO 06.2011 



The Research and Reasons 

Georgia Tech researchers Tiffany L. Chen, Chin-Hung 
King, Charles C. Kemp, and Andrea L. Thomaz produced 
research based on the touch of the Cody robot on 56 
research subjects at the world famous research university. 

The purpose of the experimentation was to develop a 
robotic nurse's assistant that could perform duties such as 
giving patients baths while in their beds. Goals of the 
research included testing and comparing nurse and patient 
interaction with robot and patient interaction, for efficacy 
and application, 

From the nurse and patient touch studies, two 
particular types of touch resurfaced: instrumental touch to 
perform a required medical task or treatment and affective 
touch to comfort patients. With human nurses, patients are 
more receptive to touch for instrumental purposes than for 
the purpose of comfort, according to the several studies. 

With the robotic nurse assistant, the researchers sought 
to determine whether the patients had the same reaction 



www.servomagazine.com/iridex.php7/magazine/article/jurie20ll_GeerHeacl 



GEERHEAD 



to the two different purposes of 
touch. The scientists also sought to 
learn whether patients preferred to 
be warned verbally by the robot 
that they were about to be touched 
and what the purpose of the touch 
was. 

The Robot 

Cody is a mobile two-armed 
robot created for testing the 
robotic nursing assistant paradigm. 
Cody's mobility is enabled by its 
Segway base, Cody's manipulators 
consist of MEKA Robotics arms 
with each one actuated by seven 
series elastic actuators at each of 
its seven joints for seven degrees of 
freedom and smooth actuation. 
Each joint also has virtual visco- 
elastic springs to ensure that the 
robot's hands stop where they 
should, 

The wrists are equally 
equipped with multiple degrees of 
freedom via six-axis force sensors. 
The hands — which look like 
spatulas — were created using a 3D 
printer. The robot touches subjects 
with cuttings of towels that have 
been wrapped around the hands 
and secured. 

The body of the robot consists 
of a torso with an RX-28 Robotis 
servo on top of that. The robot's 
intelligence consists of two Linux 
computers running the popular free 
Ubuntu Linux distribution and 
software the roboticists coded in 
with the Python programming 
language. In order for the robot to 
touch patients precisely, the 
researchers installed a tilting 
Hokuyo UTM-30LX and a Point Grey 
Firefly camera to gather laser range 
data. These are contained in an 
XBOX 360 housing. 

The robot system includes an 
interface on a remote computer so 



Cody's robot housings and 

electronics (includins power to 

the Segway), its computers, 

and controller box. 




SERVO 06.2011 11 



GEERHEAD 




the operator can choose the area of the subject that they 
wish the robot to wipe down.. Then, the robot performs the 
wiping in a fully autonomous fashion. 

A number of safety features are provided to keep 
human subjects from harm when the robot is touching 
them. The robot is mounted with a run stop button or kill 



Cody's XBOX 360 robot head containing the cameras and 
laser sensor. 



switch to stop the robot if necessary. The low stiffness in 
the robot's arms means that impact with the human 
subject is lessened. The robot controller also limits the 
downward force of the hand when wiping. Operators can 
manually command the robot to stop if the force 
measured in the robot's wrist sensor exceeds a certain 
value. 

A Robot's Touch 

The robot starts the touching behavior by making 
initial contact with the forearm, then moving the end 
effector and towel along the forearm. In the experiment, 
the researchers tested two hypotheses. First, the patient 
will accept the robot-initiated touch more if it is seen as 
instrumental to their care, rather than have it be affective 
(comforting). Second, subjects will find the touch more 
favorable when the robot gives them a verbal warning 
first. 

For the experiment, the researchers created a mock 
hospital room complete with a real hospital bed. Fifty-six 
subjects from Georgia Tech between the ages of 18 and 
29 (half male and half female) participated in the testing. 
Several tools were used to gauge the subject's reactions 
to the robot. A pre-task and post-task questionnaire was 
given. Subject's emotional states were measured using 
the Self-Assessment Manikin (SAM) and Positive and 
Negative Affect Schedule (PANAS) tests. 

The researchers also queried the participants using a 
customized Likert scale questionnaire. For this, the 
question set included things relative to the researcher's 
specific hypotheses. These included questions as to 
whether the subject was confused as to why the robot was 
touching their arm; whether they enjoyed the robot 
touching them or were scared by it; whether they were 
reassured by the robot touching them; whether they felt it 
was necessary for the robot to touch their arm; whether 
they would let the robot touch them again; and whether 



Resources 



1 



Cody robot video 

www.di3italloun9e.satech.edu/healthdndeducation/ 

index.html?nid=64852 

Georgia Tech Healthcare Robotics Lab 
http://healthcare-robotics.com 

The Segway, used for the robot's base and 

mode of transportation 

www. segway. com 

MEKA Robotics, source of Cody's arms 
http://mekabot.com 



RX-28 Robotis servo 

www.trossenrobotics.com/dynamixel-rx-28- 

robot-actuator.aspx 

The Ubuntu Linux distribution used in Cody's computers 

www.ubuntu.com 

The Python programming language official site 
www. pyt h on.org 

Cody's Hokuyo range finder 
www.hokuyo-aut.jp/02sensor/07scanner/utm_30lx.html 



12 SERVO 06.2011 



GEERHEAD 



Cody's Altec Lansing speakers that he 
uses to communicate. 



they would have preferred the 
robot not to touch them. 
Participant's faces were monitored 
by a camera, as well. 

While the subjects did like to be 
touched for instrumental reasons 
(which agreed with the researchers' 
first hypothesis), the subjects did 
not like to be warned before being 
touched (which was against the 
researchers' second hypothesis). 
This will likely play a key role in 
future research and development. 



Conclusion 



The Georgia Tech researchers are confident that the 
Cody research could lead to a real robot assistant to make 
nurses' lives easier and to help take up the slack created by 

the nursing shortage. 




The research is amply supported by Hstar Technologies, 
an NSF Graduate Research Fellowship Program, Willow 
Garage (commercial robotics firm), and NSF Grant IIS- 
0705130. SV 



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1—tf; v lawuttia 










Our resident expert on all things 
robotic is merely an email away. 
roboto@servoma3azine.com 




Tap into the sum of all human knowledge and gel ynur questions answered here! 
From software algorithms to material selection, Mr. Roboto strives to meet you 
where you are - and what more would you expect from a complex service droid? 





by 




Dennis Clark 



Update from Last Month's 
Column on Optical Mouse 
Navigation 

When last we met I was going on about using a PS2 
mouse for assistance with robot navigation. I was pretty 
sure that you could do some simple math with rectangular 
to polar coordinate transforms to get distance and heading 
information that would be more accurate than using simple 
dead-reckoning. I'm stili pretty sure this is possible, but ... 
Mr. Roboto has to-date faiied to get a PS2 mouse to listen 
and talk back, So, either my mouse is not fully functional, 
or, the lack of a datasheet for this model has put a serious 
crimp in my understanding of the protocol. Regardless, I 
have been humbled by a lowly mouse! 

I don't give up easily, but I don't bang my head 
against the wall either Since using PS2 mice is a bit tricky, 
they are getting old and hard to find, cost $5 or so, and 
finally, since there are Avago sensors available that you can 
talk to using simpfe SPI hardware, I'm going that route. 
Here is my plan and Parts List to get an opticai mouse 
sensor to be a navigation aid: 





ARTS LIST 










Part# 


Digi-Key 


Cost 


Avago ADNS-5050 Optical Sensor 


516-2261 


S1.60 


Avago AD NS-51 00-001 Trim Lens 


516-2300 


$0.57 


Avago HLMP-ED31-SV00 Red LED 


51 6*1 372 


$0/77 


Avago HLMP-5029 LED Clip 


516-1395 


S3J8 (for 10) 



As you can see (except for having to buy 10 of the LED 
clips), I could get the entire sensor setup for less than a 
cheap mouse — much less. Pius, I get the ability to take low 
resolution pictures and do lots of coof stuff with the chip 
directly. I'm going to mount this on a small proto board 
and get back with you next month with a status report on 

14 SERVO 06.2011 



how well this works. I'm also going to recycle this optica! 
mouse (with obsolete parts in it) before I lose any more 
sleep! 

Before I go on, I'd like to thank the readers for some 
truly interesting questions and problems to solve. While I 
love to solve problems and help with your robotic 
construction questions, I am still only human. Every so 
often, I receive a question that - if I were to completely 
answer it - I would have to go back to grad school and 
write a dissertation to cover it. I do enjoy a challenge, but 
please, keep your questions focused on a single issue or 
problem if possible. If it takes you three pages to cover all 
the questions, it could take me months to answer them! 




- I want to use a laptop with one or more USB 
joysticks to control my underwater ROV. But, I have 
tio idea how to code the actual reading of the 
joystickmes and buttons. Once I can get the raw data into 
a C program (preferably using gcc and public libraries), I 
can write the code to convert axis movement in forward, 
reverse, rotate, up, down, arm move, ballast, etc. Can you 
point me to the interface library and a sample interface 
code? 

— Mike 

fl. A joystick is a USB HID device and every computer 
has libraries to handle communications with a HID 
device. The tome on handling this interface is, of 
course, Jan Axelson's USB Complete. Get a copy of this 
book or check it out from your local library; everything you 
need is in there. If you are an old hand at PC programming, 
then you will have no problem interfacing with a set of 
USB joysticks. 

There are a few sites out there that can help without 
the book of course, but you'll get a lot more mileage from 
your work with USB Complete. Start by looking here: 
http://www.lvr,com/hidpage.htm. 



www. se r v o ma ga z i ne . com/i n dex .p h p ?/m ag azi n e/a rt i c I e/j u n e 2 11 Mr Roboto 




. I want to build my first robot, but I don't know 
where to start. I've looked at motors and chips to 
)Ower them. I've looked at sensors — there are a 
'nsors to choose from[ There's one for just about 
anything I would want to do. My biggest question is, what 
controller should I use? There are Netbooks, PICs, then 
Atmel, ARM, Motorola, and more. Where do I start? 

— Tom 

fl. Ask me any question but that one. Picking the 
"best" microcontroller is practically a religious 
question in the robotics community. Everyone has 
their own opinion and very good reasons to support their 
choice. Over the last 10 years, I've changed my mind many 
times. I started out with Parallax Stamps back in <mumble> 
when I was getting started again in robotics. They were 
cool after coming from using Z-80s on wire-wrapped 
motherboards using assembly language. I wanted more 
RAM and more controls, so I moved to Motorola 68HC1 1s 
and their ilk. Those were nice for a while, but I outgrew 
them, as well. I then went to the PIC16Cnnn and then the 
PICISFnnnn parts using CCS C and Microchip C compilers. 
Others really like the PICBASIC PRO compilers, which are 
also very good. 

Then, I moved to the Atmei AVR series. At first, I used 
BA5COM AVR as a teaching platform for classes because 
they did a good job abstracting the hardware layer. This is 
useful for teaching those new to the art of programming. 
Next, I discovered avr-gcc and avr-dude which ran on 
Macintosh and Linux, and freed me from Windows 
platforms. Shortly thereafter, the Arduino environment — 
also OS agnostic — came out for the Atmel ATM EGA chips, 
which is fantastic as a learning/teaching 
platform. I have not yet done much with the 
ARM platform. So far, i find the tools and 
IDEs difficult to use and even more difficult 
to explain to others. That is starting to 
change, and I'm keeping an eye on them. 

Recently, I've been attracted to the 
PIC24FJ and PIC24K series of 16-bit chips. 
They are fast and easy to use. They still need 
somewhat expensive programmers ($190 or 
so for an 1CD3), but the compiler is free. 
What is even better is that Microchip is 
coming out with MPLA8-X which is OS 
agnostic. So again, I'm interested because it 
means I don't have to develop on a Windows 
platform. As I outgrow a particular platform, 
I migrate to a higher powered, faster one. 

The processor to choose for your hobby 
will depend upon your experience with 
programming and your needs for speed. The 
development platforms that take great 
lengths to abstract the hardware (CCS C, 
PICBASIC PRO, BASCOM/AVR, Arduino) will 
be very attractive to programmers who don't 
understand hardware and those new to the 



craft. You will outgrow these only if you want to get more 
involved directly with hardware. If you don't want to invest 
a lot, then you will want to use open source compilers and 
IDEs (Integrated Development Environments) like Arduino 
and avr-gcc since you can get cheap hardware, and 
sometimes you don't need any programmers to program 
the parts. If you are going to be doing vision and object 
recognition, then you should start with the Netbook or 
laptop approach. These are the only platforms that witl have 
the computing power you'll need. 

For new roboticists or embedded enthusiasts, I 
recommend the Arduino. Cheap hardware, free 
development environment, and LOTS of user group support 
and example programs. You can then migrate to open 
source gcc compilers to get more speed, power, and 
control. Gcc is also often the environment of choice when 
you move to full-power laptops and the like to get really 
powerful robots. In the end, it is a personal decision based 
on your comfort level with working close to the hardware 
and how you choose to do it. 



afford \W 



want to put a graphical display on my robot 
controller for a fancy interface remote control. Is 
there such a thing? And more importantly, can I 
Do you have any suggestions? 

— Tony 



fl. You bet there are, and you can afford them too! 
Just for fun, I got a couple of different units and built 
the kits. The first one I found was at SparkFun. No 
surprise there. They always seem to have cool stuff. The kit 
that I got was the SparkFun Color LCD Shield LCD-09363 




SERVO 06.2011 15 




Figure 2. NKC RGB LCD Shield. 



(Figure 1)- SparkFun sells this for $40 and they have links 

to libraries for it, One library is avr-gcc friendly C. The other 
two are — as you can imagine — Arduino-based libraries 



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(Arduino calls expansion boards shields). The 
Nokia displays 4096 colors and is a 128 x 
128 pixel screen. 

Of the two color LCD boards I played 
with, this one has a slightly larger display 
(1 2" square). The native avr-gcc library runs 
faster than the Arduino ones, but the 
Arduino libraries are quite usable regardless. 
SparkFun also sells the LCD displays (Nokia 
6100) individually, so you can build your own 
boards using just the display and their 
example schematics if you want. The 
SparkFun board comes fully assembled with 
three pushbuttons and a working backlight. 
Look for it at www.sparkfun.com. 

The other color LCD display t found was 
also an Arduino shield — the NKC Electronics 
RGB LCD Shield for Arduino 65K Color Kit 
ARD-0065. This LCD display looks similar, but 
is quite a bit different from the SparkFun 
unit. The display is smaller (1" x 1"), there 
are no surface-mount parts, and the unit 
comes as a kit that needs to be assembled. 
The price is $20 — which is cheaper — but 
you have to build it- So, pick your poison. 

This LCD display also has an Arduino library written for 
it and it comes with a WAY more fancy demo program (see 
Figure 2). There are no I/O buttons on this board, and it 
too has a nice bright backlight. Maybe it was just the 
demo, but the NKC board seemed to have brighter color. Til 
have to play with them to see if this is really true. Like 
SparkFun's Nokia 6100 LCD, this display is 128 x 128 pixels. 
Unlike the Nokia display the Phillips PCF8833 compatible 
display, is a full 16-bit color device. NKC also sells just the 
LCD display for your own designs, 

I found both of these boards to be good looking and 
easy to read. The SparkFun board comes pre-built with 
buttons on it; the NKC board has to be built and has a 
slightly smaller screen, but more colors and it's cheaper. 
They both work great, however. 

Well everyone, have fun and keep building robots. I'll 
be back next month with an update on using optical mouse 
sensors for navigation - I should be able to get that project 
working at least! Until then, as usual, if you have any 
questions for Mr. Roboto, feel free to email me at 
roboto@servomagazine.com and I'll be happy to try to 
answer them! SV 



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Calendar 1 



ROBOTS NET 



Send updates, new listings, corrections, complaints, and suggestions to: steve@nccxom or FAX 972^404^0269 



Know of any robot competitions I've missed? Is your 




ROVs complete tasks related to a simulated deep- 


local school or robot group planning a contest? Send an 




water oil spill including removal of damaged riser 


email to steve@ncc.com and tell me about it. Be sure to 




pipes, well capping, and collecting water or 


include the date and location of your contest. If you have 




biological samples. 


a website with contest info, send along the URL as well, 




www.marinetech.org/rov_competition 


so we can tell everyone else about it. 






For last-minute updates and changes, you can always 


22- 


Eurobot 


find the most recent version of the Robot Competition 


27 


Astrakhan, Russia 


FAQ at Robots.net: http://robots.net/rcfaq.html 




This year, autonomous robots compete against 




— R. Steven Rainwater 




each other to stack up "pawns" on a field roughly 
based on a chess game. 


JUNE 




www.eurobot.org 


2-4 


ION Autonomous Lawnmower Competition 


25- 


International Autonomous Robot Contest 




Beavercreek, OH 


26 


San Diego County Fairgrounds, San Diego, CA 




Basic and advanced autonomous lawn mowing 




Autonomous robots navigate around fixed 




robots try to be the fastest and most accurate at 




obstacles. 




mowing a lawn while avoiding stationary and 




wwwJaroc.org 




moving obstacles. 








www.automow.com 


JULY 


3-6 


AUVS International Ground Robotics 


4- 


RoboCup Robot Soccer World Cup 




Competition 


10 


Istanbul, Turkey 




Oakland University, Rochester, Ml 




All the usual robot soccer events include software 




Autonomous ground robots must navigate an 




simulations, small robot soccer, legged robot 




outdoor obstacle course within a prescribed time 




soccer, even humanoid robot vs. human soccer. 




limit, while staying within a speed limit. 




www.robocup.org 




www.igvc.org 










s- 


BOTBALL National Tournament 


lO- 


National Underwater Robotics Challenge 


12 


Orange County, CA 


ie 


Chandler, AZ 




Student-built autonomous robots move black and 




Simulated mission to another star system. Robot 




white balls on a game board. 




probe must melt through the surface of an ice 




www.botball.org 




planet, descend into the ocean below, deploy a 








data bouy, and set up a nuclear powered AUV 


1 n 


RobotRacing 




power station, while gathering samples of any life 




University of Waterloo, Ontario, Canada 




forms found, www.h2orobots.org 




Autonomous robot car races, 
www.robotracing.org 


1 1 


Pobot Junior Cup 








Centre International de Valbonne 


12- 


AUVS International Underwater Robotics 




Sophia-Antipolis, France 


1*7 


Competition 




Events include maze solving for LEGO NXT robots 




55C Pacific TRANSDEC, San Diego, CA 




and a pick-n-place contest. 




Autonomous underwater robots must complete a 




www.pobot.org 




course with various requirements. The contest is 
being renamed to the "International RoboSub 


IB- 


MATE ROV Competition 




Competition 1 ' this year, www.auvsifoundation. 


IS 


NASA J5C Neutral Bouyancy Lab, Houston, TX 




org/AUVSI/FOUNDATION/Competitions 



18 SERVO 06.2011 








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20 SERVO 06.2011 



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PHILLIE-BUSTED 

University of Pennsylvania engineers prepared a one-armed, three- 
wheeled robot to throw out the first pitch before the Milwaukee Brewers 
game on April 20*. Philliebot pitched to the team's mascot — the Philly 
Phanatic — to draw attention to Science Day at the Ballpark. Sadly, the pitch 
didn't quite make its target, only reaching a speed of about 30 - 40 mph 
which was responded to by boos. 

PhillieBot is made out of a recycled Segway, with a pneumatic cylinder 
added. 



MORE UNMANNED HELP FOR JAPAN 

QinetfQ Group's business in North America is providing unmanned 
vehicle equipment and associated training to aid in Japan's natural 
disaster recovery efforts. QinetiQ North America's technology and 
services will allow Japan's response teams to accomplish critical and 
complex recovery tasks while remain rng a safe distance away from 
hazardous debris and other dangerous conditions, The equipment being 
staged in Japan for rapid, on-call deployment includes QinetiQ's Robotic 
Applique Kits which turn Bobcat loaders into unmanned vehicles in just 
15 minutes, The kits permit remote operation of all 70 Bobcat 
vehicle attachments, such as shovels, buckets, grapples, tree cutters, 
and tools to break through walls and doors. The unmanned loaders 
include seven cameras, night vision, thermal imagers, microphones, 
two-way radio systems, and radiation sensors, and can be operated 
from more than a mile away to safely remove rubble and debris, dig 
up buried objects, and carry smaller equipment. QinetiQ is also 
staging TALON and Dragon Runner robots in Japan in the event they 
are needed TALON robots have previously withstood rigorous 
deployment and twice daily decontamination at Ground Zero. The 
TALON robots are equipped with CBRNE (Chemical, Biological, 
Radiological, Nuclear, and Explosive) detection kits that can identify 
more than 7,500 environmental hazards including toxic industrial 
chemicals, volatile gases, radiation, and explosive risks, as well as 
temperature and air quality indicators, The TALON robots provide night 
vision, sound, and sensing capabilities from up to 1 ,000 meters away. 
QinetiQ lightweight Dragon Runner robots — designed for use in small 
spaces — will be available for investigating rubble piles, trenches, 
culverts, and tunnels.Thermal cameras and sound sensors on the 
Dragon Runners can provide data from up to 800 meters away, 
permitting the robot's ''eyes and ears" to serve in spaces too small or 
dangerous for human access. 



22 SERVO 06.2011 






MEETIE REETI 

Meet the French Reeti one of the more face-friendly robots 
around these days. Reeti talks, moves his face features, houses a 
media center PC, and reacts to touch with sensors.This quirky bot 
was built for teaching and/or amusement, and can be run on an 
iPad/iPod app. Reeti expresses an endless number of emotions thanks 
to a flexible skin and 1 5 degrees of freedom for the neck, eyes, 
mouth, and two independent eyes and ears. He gets color on his 
cheeks according to his moods, 

Reeti's two eyes are fitted with HD cameras and he has a clear 
view and a 3D perception of his environnment. His view allows him 
to identify and follow people and objects with the eyes. 

Reeti recognizes 1 words, and knows where the 
sound comes from. His synthesis speech allows him 
to speak. Connected to the Web, Reeti receives 
emails, reads for RSS feeds, and the posts on 
Facebook, Twitter, or Youtu be. His embedded PC — 
when connected to a screen — gives access to all 
the computer functions (office, multimedia, 
communication, etc.). Reeti's BluRay reader, DVD 
burner, and full connectictivity makes him a true 
Home Theater PC (full HD, audio 5, 1 , etc). 





'PACKING INTO JAPAN 

One of iRobot's Packbots was sent into the Fukushima 
Daiichi nuclear power plant to measure the amount of 
radiation and oxygen levels in the building. This is a first time 
foray into this kind of fray that is also set to check 
temperature — although the company sent the bots several 
weeks ago. A rep fromTepco claims that it will find if the 
conditions are safe for a human to enter. 



WHAT THE HECTOR? 




The University 




of Bielefeld's Department of Biological Cybernetics has unveiled a very cool looking new hexapod robot. 

Despite its sleek futuristic appearance, HECTOR (which stands for 
HExapod Cognitive auTonomously Operating Robot) is essentially a meter 
long insect. Its control program is based on the distributed intelligence 
^•^^ principle found in insect brains. Like an insect, its exoskeleton is extremely 

\^^^ light and strong, making up only 13% of its total weight (12 kg or 26 lbs). 

Developed and optimized in cooperation with the Leibniz Institute of 
Polymer Research Dresden, the carbon-fiber reinforced plastic shells 
deform less than I mm under a 30 kg (66 lb) load. Its joints, too, are 
biologically inspired; the unit's Mechatronics of Biomtmetic Actuators 
research group contributed a pair of state-of-the-art elastic joint drives 
which are being used in each of HECTOR's 20 degrees of freedom (six 
legs x3; body segments x2). 

SERVO 06.2011 23 



scours' HONOR 

The Boy Scouts of America — which offers more than 1 20 
badges ranging from archery to wilderness survival — has unveiled a 
robotics merit badge meant to promote science, technology, 
engineering, and math — fields collectively known as STEM. In doing 
so, the 101 year otd Texas-based organization is trying to remain 
relevant and better reflect boys' interests, commented Matt Myers, 
who oversees the Boy Scouts 1 STEM initiative. 

Badges have been dropped over the years — blacksmithing and 
beekeeping, for example — and replaced with new versions more in 
line with skills boys need to succeed, he said. 

"Last century, camping was an essential survival skill. Sometimes, 
you might have had to live outside in the 1900s to survive. We view 
STEM as an essential survival skill in the 21st century," Meyers 
explained. "WeVe just trying to keep relevant with what kids need to 
learn." 

Officials expect at least 10,000 of the nation's 2.7 million Boy 
Scouts to earn the new badge in the next year, compared with the 
roughly 500,000 who earn the most popular badge (first aid) each 
year.Those earning the badge will be required to design and build a robot while learning about robot movement, sensors, 
and programming. 




DEEP RECOVERY EFFORTS 

A team of autonomous underwater robots is playing a crucial role in locating 
debris and missing bodies from Air France Flight 447, which crashed into the 
Atlantic Ocean almost two years ago with 216 passengers and 12 crew members 
on board while traveling from Rio de Janeiro to Paris. 

Three robots — called REMUS 6000s — took to the water off Suape, Brazil, 
on March 25 [h with the goal of searching the seafloor until the wreckage was 
found. This was the fourth search mission in two years by investigators to locate 
the flight. 

The flight occurred back on May 31, 2009 and so far, 177 are still missing. 
Officials said that the bodies would be brought to the surface within a month. 

The REMUS 6000s — developed by researchers at the Woods Hole 
Oceanographic Institution — can dive as deep as 6,000 feet and can remain 
underwater for 20 hours at a time. 

After just a week into the planned three-month search, one of the robots - — 
or autonomous underwater vehicles (AUVs) — caught a glimpse of debris which 
was later confirmed as parts of the missing plane. Divers later discovered bodies 
from the crash that had been given up for lost. 

The debris from the flight was found about 600 miles off the coast of Brazil, at 
a site no farther than six miles from the last-known location of Air France Flight 
447, according to the New York Times. 

About I 3 feet in length and 28 inches in diameter, each torpedo-shaped 
autonomous vehicle emits a sonar beam that scans up to 600 meters on either 
side as it travels along the sea floor. The robots are programmed to move in long 
overlapping lanes — - a process the team dubbed "mowing the lawn" — and use 
their sonar to create a broad overview of the landscape. The bots can return to 
areas of interest for a closer look using high resolution cameras located on their bellies 





24 SERVO 06.2011 



CATCH SOME JOE 

The DLR's (German Aerospace Agency) flagship robot, 
Roll in' Justin, can now catch balls thrown in its direction 
with more than 80% accuracy. The robot is able to track 
and calculate the flight path of two balls thrown towards it 
simultaneously. It can reliably position its hands to within 2 
cm of the ball's estimated catch point in space in just five 
milliseconds. This task is so intense that Justin must make 
use of external computers to handle some of the 
processing, but it's only a matter of time before robots will 
have onboard computers that can do this kind of job with 
no strings attached. It seems the notion of a household 
robot that can play catch with the kids or dog isn't too 
farfetched. 

Justin can also prepare a cup of coffee using a standard 
coffee machine. He relies on the tactile sensors in his 
fingertips to detect what his eyes may not be able to see 
clearly. 





DEPLOYING FOR DONATIONS 

Tim Pryde — a 2 1 year old Product Design student graduating from 
the University of Dundee, Scotland — has created a coin-powered robot 
called DON-8r (pronounced "donator ,T ).The little robot can be deployed 
anywhere, playfully scooting around whenever someone gives it a 
donation. *'DON-8r navigates obstacles as it moves about on a random 
path for a set length of time. It then waves its flag, calls for assistance, 
and pulses with colored light until it receives another donation from a 
passer-by. Always polite, DON-8r thanks the generosity and repeats its 
journey." 

The idea is to curb the negative attitudes people may harbor 

towards human solicitors with something a bit more fun and unusual. Currently, the robot has been raising money and 

awareness for the Dundee Science Center, but it can easily be re-branded to suit any charity. 



FRIENDLY FRIDA 

ABB — a powerful Swiss automation company — has 
designed a new concept robot called FRIDA (Friendly Robot 
for Industrial Dual-arm Assembly) that can work safely 
alongside people. It's remarkably small and lightweight 
compared to the other robots in its category. In fact, it can be 
mounted on a standard workbench or hung from a wall. It can 
even be carried by its handle. For improved safety, it is covered 
in soft padding, has internal wiring, and lacks pinch points that 
can potentially trap fingers. It also has limited power and speed, 
meaning it won't break your arm if it accidentally elbows you. 
Each arm has seven degrees of freedom and an end effector 
with fingers and suction that can manipulate small parts. 
Programming is made easier thanks to automatic collision 
detection software that prevents the robot from moving in 
such a way that it could damage itself. 



M, ~~*j 




SHEAS'* 





SERVO 06.2011 25 




1 



Featured This Month 




Features 



26 BUILD REPORT: 

Moros — A 30 lb Angled 
Bar Spinner 

by Mike Jeffries 

28 POTPOURRI 3.0 

by Kevin M. Berry 

32 The Reality of TV 

by Pete Smith 
34 CARTOON 

Events 



32 April 2011 Completed 
Events 

32 July 2011 Scheduled 
Events 



BUILD REPORT 



Moros — A 30 lb Angled Bar Spinner 



by Mike Jeffries 




fores is the third generation 
lof my angled bar spinners. 
Ruiner was the original, and was 
built for RoboGames 2006 where 
it finished with a 1-2 record after 
having the antenna removed in 
the second match, which resulted 
in a forfeit in the third match. The 
weapon system was then moved 



into a much lighter chassis and 
was built to enter the 30 lb 
weight class. 

Serious weight issues and a 
frame that was too weak for the 
power of the machine kept Mr. 
Self Destruct from ever 
competing, as it lived up to its 
name one week before the event 



www.servomagazine.com/index. php?/ 
magazine/article/june2011_CombatZone 




26 SERVO -06.2011 



J 



at the Franklin Institute in 2010, 

After the complete 
destruction of Mr. Self Destruct in 
testing, the design had to be 
completely reworked. All of the 
major components were torn 
down and checked for 
functionality- The chassis was 
completely trashed, but outside of 
that, the only components that 
couldn't be reused were the 
battery packs, as they'd both been 
damaged during the explosion. 

After the damage assessment 
was completed, the redesign 
began. Taking the lessons from 
Mr, Self Destruct, Moros was 
designed. The drive system was 
moved to the front of the robot 
again - as it was with Ruiner — 
and the chassis went from a 
combination of aluminum, titanium, 
garolite, and fiberglass to waterjet 
cut 7075 aluminum. The reshaping 
of the robot allowed me to design a 
much larger amount of strength into 
the chassis. The backbone of the 
design is a plate of 1/4" 7075 
aluminum running most of the 
width of the robot, which helps 
prevent the robot from twisting and 
destroying itself. 

Once the design details were 
finished, I went to 
TearnWhyachi.com and sent 
them the drawings of the parts I 
wanted made. A few weeks later, 
a package arrived with everything 
I needed to complete the 
mechanical build of Moros. 

The majority of Moros was 
assembled over a two-day period 
in December and besides the top 
armor, it was ready to compete. 
The top armor is made of three 
layers of a composite material 
known as Zylon — the same as 
what made up the top armor on 
Mr. Self Destruct. A basic moid 
was made from plywood and 
body filler compound. Once the 
mold was completed, the material 
was laid up freehand to create 
armor in the desired shape. 

After the material finished 
curing, the armor was cut to 




> — 



Solidworks model of the 

chassis for Moros, 



Waterjet cut and 
machined parts from 
TeamWhyachi.com. 





Zylon armor curing on the plywood 
and body filler mold. 




SERVO 06.2011 27 




Moros ready for 

competition prior to 
Motorama 2011, 



shape, drilled, and painted En the 
green and black color scheme I use 
for my robots. I ran through my own 



safety inspection and determined 
that Moros was ready for 
competition at Motorama 201 1 . 



YouTube link of Moros in 
action: www.youtube.com/ 
watch?v=HoHERDQgZwo. 



POTF URRI 3.0 



This randomly timed feature 
continues to chug along. 
December '10 brought the 
unnumbered debut. Version 2.0 
appeared last February. Now it's 
June, school is out, and I've 
gathered up an uncharacteristically 
cohesive compilation. (Ed. Note: 
three words, 39 letters. In your 
face, "write at the Eighth grade 
level" people!). 

This month's theme: Kids 
Building Combat Bots Become 
Better Kids. 

Story #1: Bots II? 

The ultimate venue for kids 
building combat machines is, of 
course, BotslQ. This last 
February, a bunch of middle, 
high school, and college 
students gathered for the 
Nationals — a four-day slug fest 
of robotic destruction. From 
that rich source, Greg Munson 
shot hundreds of photos of 
machines and their people, and 
along the way captured some 
exquisite shots of the much 
touted STEM (Science, 



• by Kevin M. Berry 

Technology, Engineering, and 
Math) learning process in action. 

There's nothing that warms an 
old gearhead's heart more than the 
sight of a young boy or girl with a 
sharp, hot, dangerous tool in their 
hands! Here's my selection of 
Greg's pics from the event. The rest 
are at www.flickr.com/photos/ 
methagreg/sets/721 576261 8335 
6418 



Story #2: Five Year's 
Progress in Two 
Years - Bots to 
the Rescue! 

Nola Garcia — one of the driving 
forces behind BotslQ — gave a lead 
to a real success story. Here, in the 
words of Eddy Garcia (the principal 
of Immaculate Conception School in 
Hialeah, FL f is the tale of a young 




Hailey Russel adding essential 
letters to a 15 pound wedge 









m 






28 SERVO 06.2011 



Valentina 
Chamorro 
Watson 
trouble shoots 
a 1 5's battle 
damage. 









SERVO 06.2011 29 




The next generation getting the vision. 







'M. i 



;> 



Max Bales, Greg Bales, and Ethan Arteaga with a 

bothead's favorite tool handy. 



man, struggling in school, brought 
to the top through building and 
fighting bots. 

Eddy begins: 

"Our science teacher, Mr. 
Stephen Hanrahan, is the one that 
has worked with our students and 
had the robotics program come alive 
... Kelvin Gomez came to Immaculate 
Conception Catholic School August 
'08. He was in sixth grade and his 
reading and mathematics skills were 
at a first grade level. Our program at 
Immaculate had not really worked 
with a student that was performing 
this low ... I decided to give him an 
opportunity, but I could not make 
any guarantees. Kelvin was accepted 
into our modified program for 
students with learning disabilities. He 
is a very respectful and proper young 



man, who always has a smile on his 
face and a kind word on his lips, 
Kelvin participated in various 
activities during the remainder of his 
sixth grade year. 

"He is now in eighth grade and 
has been with the Robotics program 
since seventh grade. His will to 
succeed has helped him overcome 
many barriers, and he is currently 
performing at a sixth grade reading 
and mathematics level. 

Mr. Hanrahan says, "I don't treat 
Kelvin as if he had any learning 
differences. If he is on the robotics 
team, he has to perform at the level 
of all his peers," Most of his peers on 
the team are in Honors Program 
classes. He has built a remarkable 
relationship them in the past two 
years. 



TT~ 




Garcia also notes that Kelvin is a 
"kinesthetic and auditory learner." 
This means he learns better from 
hearing things repeated by others, 
and having his hands on the job. 
Sitting and reading isn't this kind of 
learner's strong suit, but building 
robots sure seems to be! 

Story #3: The Pink 
Team Helps the Thin 
Blue Line 

This story is summarized from a 
press release from the Brevard 
County Florida School Board; the 
Pink Team's website, NASA, and 
teacher's blogs. 

When Detective Christopher 
Cochie from the Rockledge Police 
Department, FL, first approached 
FIRST Robotic Competition (FRC) 
Team 233 ("The Pink Team") to help 
build a robot for his SWAT team, he 
had something fairly simple in mind, 
like a remote controlled miniature 
car with a camera mounded on the 
hood. The team took his ideas, 
added some of their own, and came 
back to him instead with a state-of- 
the-art robot that could climb up 
steps, trudge through mud, toss a 
phone, launch flash bangs, and do 
much more, which they dubbed the 
"PDbot" 

Its creators were well versed in 
the mechanics of robotics, thanks to 
the competitions they'd participated 
in. Given the chance to help their 



30 SERVO 06.2011 




local police officers, they jumped at 
the opportunity; they enlisted the 
help of their teacher and FIRST 
mentor Marian Passmore, and their 
FIRST sponsor, NASA's Kennedy 
Space Center Engineering 
Directorate. (Team members were 
mostly from the several high schools 
in the Kennedy Space Center area.) 

The PDbot weighs 
approximately 100 pounds. Hidden 
in its compact frame lie many 
systems designed to assist officers, It 
can be operated remotely up to 500 
feet through an urban environment, 
where operators use visual feedback 
from the portable driver's station. 
There is also a speaker and 
microphone mounted on the robot 
that allows for two-way audio. The 
unit is weatherproof to a certain 
degree, and intended to withstand 
the moisture, rain, and heat of the 
Floridian environment. The robot has 
a camera with day and night 
capability, and onboard video 
recording. In low light situations, it is 
assisted by infrared LEDs and an 
infrared spotlight. It also has an 
extremely powerful floodlight which 
can light up its surroundings like it is 
day, while obscuring the vision of 
those who looks in its path. On its 
back, the robot carries the standard 
police throw-phone. 

The robot's strong motors and 
tank treads drag its cord behind 
without trouble, as the machine has 
proven its force by dragging an 
officer across the ground with 
inhuman ease. PDbot's off-road 
prowess lets it navigate steep 
inclines and vegetation, and even 
climb some types of stairs. Anything 
that fits in the space — like medical 
supplies - can be strapped on for 
delivery use. The robot has two 
pneumatic canister launchers with 
short and long range settings that 
can launch different types of 
grenades, including flash-bang and 
tear gas, as well as the police's own 
camera ball. 

A next version PDbot is under 
development and will streamline and 
simplify the design, while bringing 



new capabilities. It will 
add full duplex audio, 
an attachment to 
break through glass 
doors, a revised and 
more portable driver's 
station, a taser, and 
more. These additional 
features will help to 
further educate the 
robotics team in 
teamwork, 
construction, design, 
and software. Long 
range plans include 
offering a "kit" for sale 
to other robotics teams 
that they could sell to 
their local police 
department. Their 
company's website is 
www.roccobotks. 
com. 




Kennedy Space Center's Engineering Directorate and 

students from the FIRST Robotics Pink Team 

developed a life-saving robot for the Rockledge, FL t 

Police Department. {Photo credit: NASA.) 



Story #4: Yes, 
Virginia, You Can 
be a Bothead and a 
Beauty Queen 

This one is from my own 
experience with girls building and 
fighting combat bots. 

My #3 child - who's been 
fighting bots since she was nine — 
was also into (along with our whole 
family) Odyssey Of The Mind — a 
creativity competition. When she 
was 1 5, her high school team did a 
Three Stooges skit that required a 
technical element. The team wanted 
a life-sized mannequin doing the 
Curly "top of the head 
slap" but had no idea 
how to build it. She 
asked me, "Dad, do you 
mind if I tear apart my 
robot?" So, she gutted 
herantwetght, and 
built a remote 
controlled mechanism 
to drive a slapping 
hand on top of Curly's 
head, 

Cut to the 
competition. Her part 
was Beauty Queen. Long 



dress, high heels, tiara, dozen roses. 
The judge (a big hairy manly man) 
asked her condescendingly, "Honey, 
what part did you have in getting 
ready?" She proceeded to give him a 
highly technical lesson on modifying 
servos for continuous rotation, R/C 
switches, building a custom battery 
pack to set the voltage/speed, and 
converting rotary motion into linear 
motion through a sliding linkage. 

Silent room. For a long time. 

First place. 

And yes, I'm a proud dad. 

The conclusion: (so, Kevin, 
what are you really trying to say?) 
kids building combat bots DO 
become better kids! 




PDbot teams up with Rockledge, FL officers. 
(Photo credit: Norm Morgan.) 



SERVO 06.2011 31 



EVENTS 



Completed Events for April 2011 




Seattle 
center 



SeattleBotBattles 9 was 
presented by Western Allied 
Robotics at the Seattle Center on 
April 10th. Eighteen bots were 
registered. 

Central Illinois Bot Brawl 201 1 
was presented by the Central 
Illinois Robotics Club in Peoria, IL 



C entral Illinoi s 

gird 

Robotics Club 



on April 2nd. Twenty-six bots were 
registered. 



IHEnfiSS 



RoboGames 201 1 was presented 
at the San Mateo, CA 
Fairgrounds on April 1 5th -17th, 
2011. 



Scheduled Events 
for July 2011 



Ichiele Museum Clash Of The 
'Bots 2 will be presented by 

Carolina Combat Robots in 

Gastonia, NC on July 23rd 201 1 . 

Go to www.carolinacombat.com 

for details. 




THE REALITY 




FTV 



Combat robotics started for most 
people when they first saw it on 
TV. Shows like Robot Wars, 
BattleBots, and Robotica brought 
the sport to an audience of tens of 
millions every week, and there 
were Battle Bot toys and even 
McDonalds gave miniature ones 
away with Happy Meals. It was big 
business. 

However, this success came at 
a price. Dollar signs were flashing 
in front of some people's eyes and 
lawsuits over the concept drove the 
Robot Wars show over to the UK 
while the issue was battled out in 
court for years, Money was 
promised to competitors and not 
paid r competitions were long, 
drawn out affairs where you would 
have to spend a week in San 
Francisco or London, and you might 
not even get on the show. The 
beginning of the end was an ill- 
advised lawsuit over a Super Bowl 
advertisement, then the death knell 
was when Comedy Central misread 
their audience demographics and 



i An Opinion Piece by Pete Smith 

moved the show to late evening 
and tried to sex It up to suit a 
teenage male audience. This drove 
away the younger kids and their 
fathers, and while audience figures 
were still respectable, the show 
was axed when internal changes 
within Comedy Central made it a 
bad fit with the rest of their 
programming. 

Without the money and lure of 
TV, competitor numbers dropped 
off, bots were damaged or 
destroyed and not rebuilt, and 
many moved onto other hobbies or 
work (several of The Mythbusters' 
team had competed, and Grant 
Imahara even wrote a book on the 
subject called Kickin' Bot: An 
illustrated Guide to Building 
Combat Robots). 

Today, there is a core of several 
hundred keen amateurs that still 
build and compete — mainly in the 
USA, Brazil, UK, and Australia (but 
many other countries, as well) — 
and there has been a big rise in the 
number of bots in the smaller 



weight classes. The big 220 lb 
heavyweights only compete in a 
couple of events a year. 

This year, however, sees the 
possibility of the return of the sport 
to mainstream TV with the 
recording of the heavyweights at 
the 201 1 RoboGames in San 
Mateo, CA. The exact format of 
the program was still unknown at 
the time of this writing, but I'll bet 
it is more likely to be in the format 
of a reality TV show, rather than a 
strict competition. 

With this in mind, a TV 
recording crew came to visit with 
Team Moon (Billy Moon and Dick 
Stuplich) in Cary, NC. I had been 
helping Billy build a new big bar 
spinner and had actually recorded a 
lot of this build with a video 
camera the producers had sent a 
couple of weeks before they 
arrived. I went along on the day of 
recording to see what was involved 
in putting together a TV show. 

The crew showed up around 
8.00 AM and consisted of four 



32 SERVO 06.2011 






people: a cameraman, a soundman, 
the director, and a personal 
assistant. All but the director were a 
local crew. She was from Australia 
and had the whole day planned 
out, working to a preset storyline 
and filming plan. 

First, was an interview (Figure 
1), with Billy and Dick about the 
themed multi bot "Death and 
Taxes." How it had performed at the 
event last year, what had gone 
wrong (Taxes had burst into flames 
in a rather spectacular way), what 
modifications were planned, the 
tactics they planned to use, and the 
perceived weaknesses and 
strengths of the other featured 
robots were among the questions 
asked. Each question was often 
asked several times until the 
director got the answer phrased the 



* m **\ lift**.. 




Figure 3, Making Ti sparks 



right way, so the interview could be 
edited so it sounded more like a 
conversation. (This is amazingly 
time consuming!) 

Next came a staged rebuild of 
the old bot into a new chassis 
(Figure 2) with the improvements 
being shown as the bufld 
progressed. Once again, parts were 
repeated to get the right shot, and 
often the action would be filmed 
and then Billy and Dick would have 
to repeat the description of what 
they were doing, but speak directly 
to the camera. 

The crew then filmed a few 
eye-catching shots with the ever 
popular titanium sparks 
(Figure 3) and a flame 
test of battery padding 
material (Figure 4) 
before moving out to the 

street for a test drive 

(Figure 5), This is 

where things got a 

little "interesting." 

The crew posted signs 

on street lamps which 

stated that if you 

were on the street, 

you consented to 

being recorded. The 

poor assistant had to 

get anyone that just 

happened to pass by 

to sign a disclaimer 

form. This all got 

rather hectic when a 

couple school busses 

dropped kids at the 

end of the street and 

a crowd started to 

gather. 

It soon became 



clear that the crew didn't really 

understand the lethal potential of 
these robot machines, and they had 
to be told several times that testing 
the weapon with an audience of 
kids and no arena was not a good 
idea. 

The day wrapped up after a 
good eight hours of recording that 
would be condensed down to only 
a few minutes in the final show. It 
will be interesting to see if this is 
the start of something big in the 
sport or just a one-off. Hopefully, it 
will be be the start of a long, 
mutually advantageous love affair 
Of course, only time will tell. 





4h w 




Figure 4. Flame test. 




SERVO 06.2011 33 



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SERVO 06.2011 35 




by Mark Mitchell 



Part 2 



Having visibility into an SPI bus is a very convenient and sometimes necessary 
feature when working with microcontrollers. Last month, we started a project that 
provides the desired "peek under the hood" with a tool that accesses and excites the 
SPI bus and also provides a UART logic level shifter for easy connection to a serial 
port from your micro. 



www.servomagazine.com/index.php?/magazine/article/june2011_Mitcheil 



Our goal this month is to finish off the monitor by 
updating a few features and to put it in a useable housing. 
First, we'll wrap up the hardware for the project by putting 
it in a box. The enclosure will make the unit more robust 
and attractive, thus providing a handy test tool for the lab. 

Next, we will implement a FIFO (First In First Out) 



buffer in the firmware to enhance the speed and usability 
of the board. The FIFO will allow longer data sequences to 
be monitored and allow better speed performance on the 
monitor's SPI port, SPI has several flavors that are used by 
different devices. These are referred to as the operating 
modes. We will add the ability to configure these modes so 
that most SPI devices can be used. 



FIGURE 1. Top of 

the modified board 




FIGURE 2. Bottom 

of the modified board. 




36 SERVO 06.2011 





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» 1 








^^^H - ^v — 

















The first version of the code allowed a straight 
dumping of the SPI contents to the terminal Now, we will 
add a very simple menu to accommodate some simple 
configurations to complete the unit. 

Hardware 

The first thing to do is to drop the circuit board into a 
box, ! found a small inexpensive box from Hammond and 
decided to mount the board in the lid. Having the great 
benefit of hindsight, it probably would have been wiser to 
have figured out hole positions and such before building 
the circuit, but where is the fun in that? I decided to 
remove the connectors for the SPI ports and the UART, and 
place them on the other side of the board. This way, the 
board could be mounted in the lid with the connectors 
passing through holes in the lid, This approach provides a 
secure and convenient way to mount the board and still 
access the connectors easily, 

I chose headers with locking ramps for the SPI and 
UART connectors in a mostly seif-defense choice since I 
have inserted too many un-keyed connectors backwards in 
my history and generally did not enjoy the results. Also, 
since the connectors that plug in here are color-coded clips, 
I did not want to confuse things by allowing more than one 
orientation, 

The replacement of the headers required a little bit of 
rewiring because I flipped them to the other side of the 
board and moved the position of two of them to have a 
better layout in the lid. This was managed quite easily and 
quickly. This is shown in Figure 1 and Figure 2. 

Next, I laid out and drilled holes in the lid so that the 
connectors would pass through, and ! also created 
mounting holes for the board. I found some appropriate 
locations for some 4-40 screws in the board corners and 
drilled holes in that. Assembly of the box was as simple as 
securing the 4-40 screws through the mounting holes in the 
lid, tightening a nut on the inside to act as a standoff for 
the board, and placing the board in place, I then secured it 
with another nut on each screw. Figure 3 shows the lid 



FIGURE 4. 

Cable 
entry and 

inside view. 




after cutting. The oval slots were made with drill holes and 
I milled the slot between the holes with a Dremel milling 
bit, my drill press, and some patience. 

There are basically two more wired connections to the 
board from the outside world which are the power supply 
connections and the RS-232 port. Both of these were 
handled by drilling holes in the side panel, passing a cable 
through the panel with a grommet clinching the cable. I 
chose to solder these wires directly to the existing pins to 
save a connector, since this was to be a fairly permanent 
installation. Figure 4 shows a view of this. 

The connectors were configured the same as they were 
originally, just oriented in different locations. Figure 5 
shows the new positions. Operation is the same as in last 
month's article (Part 1) with respect to connector 
attachment and configuration. 

I made a label using the ExpressPCB circuit board layout 
tool and printed it onto label material. The label was placed 



GHD TX RX 

SDI UART 
SCK 

ss 



GHD 

SDO 
SCK 



SPI IN 



SPI OUT 



FIGURE 5. Connector locations, 
pin-outs, and label diagram. 



SPI/UART MONITOR 



SERVO 06.2011 37 




down on the board after having the connector 
slots cut out. This allowed a cleaner look at 
the connectors and simple labeling. 

The completed hardware is shown in 
Figure 6 and Figure 7. 

Software 

The next challenge was to update the 
firmware with a FIFO to allow for improved 
performance over the simple operation in the 
original design, The idea is that by adding 
some form of buffering, a larger number of 
bytes in a transmission can be monitored. The 
bottleneck here is the speed of the UART in 
getting the detected SPI bytes out to the 
terminal. The PIC is limited to using 57600 
baud maximum, so if we buffer up the bits 
we can collect them from the SPI bus while 
we are pumping them out to the PC. A FIFO 





FIGURE 7. Completed project. JI^B^^^^^^^ 

fc ^^-^^^S, M ' **^^ 9pi ait JJ 




'MM t! 

IP 


1 ^v\ M M 









tf 

// 
if 



SPI Incerup- hindl*r 
uhis function r.ar.ages LncoaiiTig api crafiic and pvza ±z in che fi's 



piax,_SS7 

void SSP_i«£ ( 

ff handle, activity AA *yilc **£lal past 



FIGURE 8. FIFO fill code. 



// if «pi byes is ready, 
if ipi_data_is__in 






// g*i th* byt* *a itici: it in tbt d«t» baff«i (FIFO 

D*t*3uJf er . Inroi ' ■ »pi_=«ad 

// confuse tftat we have net exceeded the buffer alse, if so wrap around to szixz 

if InPos KftXCUSUiSIZa 

InPsfl ■ 0; 

InPo*-T. 

// add this itan to ccuTst ikeapa acraclc □ £ bytes in queue!' 

It*nCo\int+4. 



SPI Mode Configuration 



DATA 



The modes for the SPI bus can be a bit confusing partly 
because of the terminology, but it is really quite straightforward. 
There are four basic operating modes logically named: 0, 1, 2, and 
3. These simply refer to the combinations of whether the clock 
signal idles low or idles high, and whether the data is latched into 
the receiving device on the rising edge or falling edge of the clock. 
(Please refer to Figure A for discussion.) 

When data is sent out of the SPI port, the dock starts out in 
an idle state. This state is set by the CPOL signal. This can be seen 
in Figure A, where the CPOL signal is 0. The clock starts out low 
and ends low, and when the CPOL is 1, the clock starts out high 
and ends high. 

When data is sent out of the SPI port, the clock edge selected 
by CPHA latches the data in the middle of the active data time 
using either the rising edge (CPHA = 0) or falling edge (CPHA = 1). 
In addition, this defines when the data line transitions to the next 
bit (the X part of the waveform in Figure A) which occurs on the 
opposite edge of where the data is latched on. 



mode: ■ 



MODt 



ht-|_j 



i_r 



)CZ>OC 



i i i 



DATA 



3C3CZX 



CPOL ■ 
CPHA - & 



MODE = ) 



CPOL » 1 
CPH& - B 



nOBE = 3 



CL* 



n 



CLK 



i J 






DATA 



)CDCDC 



1 i l 
»^»ZDCZ)CDCZ3C 



CPOL - 8 
CPHA = 1 



CPOL = ] 
CPHA - 1 



CPOL - »L? Idle state uHierr clock is not transit? on jng 
CPHA - Sets which clock edge data is latched on 



FIGURE A. 



38 SERVO 06.2011 



buffer is a perfect choice for 
this feature. The 
SPI data fills the FIFO by a 
simple read into the FIFO when 
the bytes appear at the SPI 
input port. The FIFO is drained 
by the program as it sends the 
data out to the PC via the PIC's 
UART using prlntf statements. I 



// loop forever 
while FDSSVEH 

( 

// output the current byte in the output count 
Bp±~K Out3yte 
delay_ins :!? ; 

// inc cut put: byte to next value 
Out By t* +4,- 



FIGURE 9. FIFO drain code. 



chose to put the SP! FIFO filling 
portion in an interrupt handler 
which is very easy to use in the 
CCS environment. The F!FO 
drain capability resides right in 
the main loop of code (in fact, 
it does little else). The code 
sections are shown in Figure 8 
and Figure 9 

The FIFO is implemented as 
a buffer of 60 bytes called 
Data Buffer, The incoming SPI 
byte is inserted into the 
Data Buffer (an array) at the 
current location pointed to by 
the InPos index. After this, the 
index pointer is checked to see 
if it is at the end of the FIFO 
and if so, the index is wrapped 
back to the top position in the 
FIFO (set to 0). 

The drain operation works 
similarly, except the data is 
removed from the currently 
pointed to location via OutPos. OutPos is then checked to 
see if it is at the end and if so, it is reset to the top. This is 
elaborated on in Figure 10. That pretty much covers the 
FIFO part 

The next item to handle was the configuration of the 
SPI bus. It seems to me that there is always one element of 
a project that appears to be straightforward and then 
turns into a snake pit. That was the case here. I 
wanted to implement the SPI configuration as fully as 
I could, so the goal was to cover all of the four 
operating modes in the SPI bus standard. These 
modes are covered in more detail in the sidebar "SPI 
Modes." 

Because I had implemented the SPi receiver on 
the hardware SPI port, the setup of CPOL and CPHA 
signalling was just a matter of setting the appropriate 
bits in the registers for that port. Microchip has kind 
of a funny way of labeling these signals in the 
registers which required significant noodling to get 
right (and Googling), On the transmitter side, I had 
implemented the port using the built-in functions for a 
soft SPI interface, I was not able to figure out how to 
change the settings of the port at run time since the 
port configuration is done through a compiler 
directive. So, in order to complete my mission, I had 
to write a bit-banged SPI transmitter which appears in 



// This cede implements the drain function of Che FiFC 

// check if a byte is available in the fifo (itemcount >0) 



i f | It emCenirit > • 

I 

// be sura aa have net exceed the buffer aize, if ao report 
if 'ItemCount > MAXQUSUSSIZi,: 
{ // vs have a buffer Overrun 
ptirttf "Buffer Ov6icvm\i\rt m t i 

I 

// format output by inserting a new line if 1€ bytea have been printed 

HevLineCeuntTt ; 

i f Ke vl ine Count —■ 16 ) 

{ 

// output che byte out the usrt plus a return to elign tc 16 ayitbolg wrde printout 
priivtf " \ ix\x\o* , DetaEuf f e: 'OutPoa 5 ) * 

NevLineCount ■ ; 

} 
else 

i 

// output the byte out the usit 

jasintf "list", DataBuf fes ;OutPoa| > ; 

} 

/ .' remove the lest byte printed f rem th buffer (item count and reposition buffer pointers) 

ItemCouat — ; 

if OutPos .--> KAXQUSUESIZS 

OutPoa = Q; 
else 

OutSoa-r-,- 



the listing in Figure 11. 

After considerable head scratching, I managed to get 
the bits on and off at the right times and voila ,-... data was 
flowing. I tested the process by pumping out the data from 
the SPI port and looping it back to the receive side. I also 
monitored the data lines with a scope. 




FIFO Operation Diagram 



FIFO 







I V*Tf. fl 




I *m i 




I jvti a 




f" 


JlCTf 3 




1 Iffl list 





(!j>.Poi 




nPoi (illl from top t)c«n, Loops back to top 



OutPos drains rro* top ttoum, loops each to too 



FIGURE 10. FIFO operation diagram. 



SERVO 06.2011 39 



// check clock polarity desir*d ( this determines the starting clock level 
// if cpcl ia the clack idles law. 
if epel « 0) 



output_bit CLK, 0) i 



} 
else 

{ 

output_bic CLK. 

} 

// init the bit cauntes 

Sit - 0; 

// set up the data (DOUTJ pin to be the same as bit of data 

eutput_bit DOUT bit_teat data, Bit) ); 

// drive the chip «nahln line lev 

output_bit !CE, Oj ; 

// delay iCfiak setup time 

dalay^ua 

// Lcop through each bit te^glirtg th* clock *nd updating the data bit such chat the 
// data is valid on the rising edge for cpha = 
if cpha ™ 0) 

t 

whil* Sit < 9) 

I 

suipu: toggla CLK ; 

delay_ua 100 ; 

Bit++, 

output J&it DO0T, bi Latest data, Bit) ) ) ; 

output^toggle CLK . 

delay_us ;100) ; 

} 
J 

else 

* 

// Loop thrcugh each bit to-ggling the deck and updating the data bit such that the 
// data ia valid on the falling edge for cpha = 1 
while Bit < 3) 



ouxpuc toggle CLK 

del*y_u* 100) ; 

cutputtoggle CLK 

del*y_u* 100) ; 

Bit—. 

output_bit DOUI,bit__t*at data. Bit 



FIGURE 11. 

Implementation of 
bit-banged SPI port. 



i 



} 

// vhan all 9 bits are done finish off 
output_hit DOUI , J ; 
output bit . CE, 1 > i 



ieceived/bent data 



SPI/UART Monitor Ver 2.0 



Mode Set — 


- Clk idle low, d- 


Coismands — 




ir.0<ret> - SPI 


Mode 1 


rol<ret> - SPI 


Mode 1 


m2<ret> - SPI 


Mode 1 


m3<ret> - SPI 


Mode 1 


gg<ret> - Go ■ 


- start execution 



FIGURE 12. 

User interface 

menu. 



95 

Cmd = g Cede = g 

Waiting for data. . . 

I 00 I 01 1 02 | 03 | 04 1 05 | 06 I 07 | OS | 09 | 0a | 0b { 0c | Od | Oe I Of 
1 10 1 1 1 1 12 1 13 1 14 1 15 1 16 1 17 1 18 1 19 | la | lb 1 1c f Id | le | If 
I 20 1 21 1 22 | 23 1 24 | 25 | 26 1 27 | 23 [ 29 I 2a | 2b 1 2c | 2d I 2e J 2f 
| 30 | 31 1 32 | 33 I 34 | 35 1 36 1 37 J 33 1 39 1 3a | 3b J 3c | 3d j 3e ( 3f 
I 40 J 41 1 42 | 43 | 44 | 45 | 46 t 47 | 48 J 4914a | 4b} 4c I 4d | 4ej4f 



Modern lines 



" 



CD 



Rl 



DSR # CTS r DTR T RTS 



The last item was to configure 
the SPI settings from the terminal — 
perhaps the world's tiniest and 
simplest user interface. I created a 
small set of commands to set the 
various operating modes and printed 
out a very short menu to the 
terminal. This is shown in Figure 12. 
Upon reset, the menu is displayed 
and the program waits until you enter 
a command, which either sets the 
mode of the SPI bus or initiates 
operation. The monitoring proceeds 
until the user resets the processor 
(through a power cycle). 

Future 



l 2 C functionality could be added 
to the system quite easily by tweaking 
the hardware for the SPI port to 
include appropriate pull-ups and 
updating the software to read the PC 
protocol. The prototype boards allow 
easy rip-up and replace so this would 
not be a big deal 

The current processor only has 
256 bytes of RAM, but other devices 
are available up to 1,024 bytes and 
an internal oscillator of 32 MHz. 
Moving into the PIC 18F family or 
perhaps an Arduino would allow for a 
much more powerful system. 
So, that concludes the SPI 
monitor project. Full details are 
available on the website if you 
want to construct your own. 
There is plenty of opportunity 
for improvement if you have any 
ideas. SV 



CCS Compiler 
www.ccsinfo.com 

Microchip 
www.microchip.com 

BoardworX System 
www. boa rdworxsy stem .com 

Project Details 

markmitchell@mx2 

systems.com 



40 SERVO 06.2011 




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Building 
From Found Parts 

by Gordon McComb 

"Found parts" are things you find around the house — or garage or hardware 
store or any place else — that are just begging to be used in your next robot. 
Found parts can help reduce the costs of building a bot. Plus, if the part can be 
used as-is without cutting, it makes building the robot easier. You don't need as 
many tools for construction. 

www.servomagazinexom/index.php?/magazine/article/june2Q11 JUcComb 



Toys are among the most popular form of found parts. 
If you've been building automatons for any length of 
time, no doubt you've got a few repurposed K'NEX 
or Erector sets driving around your living room. There's 
virtually no limit to the number and type of found items 
you can use in your robotics projects — either as the body 
of the robot or as a main part. 

In this article, I'll talk about making a small robot using 
a pre-shaped piece of metal commonly found at any home 
improvement store. It's already in the shape and size for a 
bot, so there's nothing to cut. You'll drill a few extra holes, 
mount some motors and a caster, and you're done. 
Construction time is 30 minutes or less. 

Introducing the "No-cut" 
Robot Base Philosophy 

Of all the aspects of robot building, cutting stuff up is 
my least favorite — especially if it involves metal. Many 



Tamiya gearbox 
motor (X2) 
See text "X^ 



FIGURE 1. Design layout for the Mini T-Bot. It uses a 6" 

T-shaped galvanized steel strap, found in the 

lumber section of your nearby hardware or home 

improvement store. 



|-_-_v_- 



=e 



Simpson 66T 
nail strap 




O 



o 



O 



Hole for skid 



robot designs use stock metal of some kind: U-channel, 
tubing, strips, or large plates that must be cut down to size. 

But what if you could find metal already in the shape 
you need for building your robot? You can, but this stuff is 
found in a different part of the hardware store than the 
stock metal bins. With it, you can construct "no-cut" metal 
platforms that require no — or at the least, very little — 
cutting. 

The basic idea behind the no-cut is to use base 
materials that are already at or very near the proper size 
and shape. The parts of the robot — the motors, sensors, 
batteries, and so forth — can then be attached using 
fasteners, glue, hook-and-loop, double-sided foam tape, tie- 
wraps, or other techniques. The concept of the no-cut 
seems simple (and obvious) enough, but it does require 
thinking out of the box to identify ready-made things that 
you can repurpose. 

The Mini T-Bot we'll describe here is an example of a 
no-cut mobile robot. It uses a readily available - and 

inexpensively priced — 6" strapping T 
(also spelled tee), commonly used to 
lash together pieces of lumber in a 
home. The basic layout for the Mini T- 
Bot is shown in Figure 1. 

Look for strapping Ts in the lumber 
section of your local hardware or home 
improvement store. Strapping Ts are 
available in numerous sizes; the 6" size 
is the smallest that I've seen, but they 
are also available up to 16". The size 
measures the crossbar at the top of the 
T; the vertical or stem portion of the T is 
in various lengths, depending on design. 

One popular strapping T is the 
Simpson Strong-Tie T Strap; I purchased 
mine at the local Home Depot, but they 
are sold at many local and online 
hardware stores. The brand doesn't 
matter; anything similar will do. 
The Mini T-Bot uses the Simpson 



1.5" dia wheels 

from dollar store 

toy 



42 SERVO 06.2011 



66T, made of 14 gauge galvanized steel. The T 
measures 6" x 5" with a strap width of 1-1/2", The 
66T — like most strapping Ts — already has holes in 
it for nailing. The holes are offset and most will 
not line up with hardware you want to hang on 
your robot, so you'll need to drill new holes. A 
power drill (or better yet, a drill press) is 
recommended for drilling the holes. 

Constructing the 
Mini T-Bot 

The Mini T-Bot requires a few extra parts in 

addition to the strapping T and assorted fastening 
hardware. You are, of course, free to substitute 
these for others you may have on hand or like 
better. 

You need two each of the following: 

• Tamiya three-speed crank axle gearbox 
motor, #70093. 

• Plastic wheels from a dollar store toy; 1-1/2" 
to 2" diameter, 2 mm bore hub. 



The Tamiya parts can be purchased from most any 
online hobby retailer; see Sources for a selected list. The 
motors are mounted on the ends of the crossbar. To keep 
the cost of construction to a bare minimum, I've used a 
non-rotating skid for balancing the other end of the robot. 
The skid is nothing more than a 6-32 x 1/2" machine screw, 
hex nut, and steel or nylon acorn (cap) nut. The roundness 
of the acorn nut provides a smooth gliding surface. 

For your reference, the finished Mini T-Bot is shown in 
Figure 2. 

Begin by assembling the two gear motors according to 
their included instructions. With the Tamiya three-speed 
crank axle gearbox, you can select any of three gear ratios: 
17:1, 58:1, and 204:1, The 204:1 ratio makes for a fairly 
slow bot, but it offers the most power for trekking through 
dense carpet. Try the 58:1 speed, which should be 
acceptable as long as the robot isn't unnecessarily weighed 
down. You can always disassemble the motors and change 
the gear ratio. 

After building the gearboxes, don't snap in the motors 
just yet. Use the included tube of grease to lubricate the 
gears. Be sure to wash your hands to remove any grease 
residue before continuing with the rest of the construction. 

For my prototype, I used a pair of 1-1/2" diameter 
(1/4" tread width) wheels \ pulled off a toy purchased at 
the nearby dollar store. The bore in the hub of the wheel 
was already just the right diameter for the 3 mm hex axle 
used with the gearbox motors. If your wheels have a small 
bore, carefully drill it out to the proper size. Don't make it 
too large, or else the axle will simply spin inside the wheel 

Cut the axle to about 2-3/8" in length. Use a small 
hammer to gentty tap the axle into the bore of the wheel. 
Then, secure the axle inside the motor using the included 
setscrew. Use your fingers to manually rotate the gears so 
that the setscrew is accessible from the top of the motor 



FIGURE 2. The constructed Mini T-Bot, 

with a pair of Tamiya three-speed crank 

axle gearbox motors, small wheels 

pulled from a dollar store toy, and a 

non-rotating skid. 




(the bottom has the two flange eyelets for mounting). 
Slide the axle so that there's about 5/8" clearance 
between the side of the motor and the inside rim of the 
wheel (see Figure 3). Use the included hex key wrench to 
tighten (but don't over-tighten t) the setscrew to hold the 
axle in place. Remember that you're constructing a left and 
right motor. The difference is whether the wheel is 
attached to the left or right side of the axle. 



Here are selected sources for the Tamiya motors, wheels, and 
ball caster detailed for the Mini T-Bot, plus online sellers of 
motor bridge modules: 



Parallax - vnyw.paraltax.com 
Motor bridge modules. 



Sources 



Polo I u - www.potofu.com 

Tamiya motors, wheels, and other accessories; selection of 

motor bridge modules; high efficiency replacements for FA-130 

motors. 

Robots hop - www.robotshop.com 

Tamiya motors, wheels, and other accessories; DFRobot 

Arduino motor bridge; other motor bridge modules. 

Robot Store/ Jameco - www.robotstore.com 

Selection of Tamiya motors and wheels; L298 motor bridge 

chip; and assorted components. 

Sotarbotics - www.sotarbotics.com 

Tamiya motors, wheels, and accessories; motor bridge modules; 

high efficiency replacements for FA-130 motors. 

Spark Fun - www, sparkfun.com 

Motor bridge modules; breakout boards; and chip-level 

controllers. 

The Robot Marketplace - www.robotmarketptace.com 

Tamiya motors, wheels, and other accessories; motor 
controllers. 

Tower Hobbies - www.towerhobbies.com 

Full line of Tamiya products. 



SERVO 06.2011 43 




Cut shaft 
to 2-3/8" 




FIGURE 3, 

Make a left 
and a right 
motor, 
placins the 
wheels on 
opposite 
ends of 
the motor 
axle* 





Left motor 



Right motor 



Only a few holes need to be drilled in the strapping T 
to secure the motors. Use a 9/64" drill bit to make holes for 
4-40 x 1/4" or 4-40 x 3/8" machine screws. The small 
fasteners and the somewhat larger holes provide some 
"slop" in mounting. 

For each motor, position it near the end of the crossbar 
where you want it to go. Use the mounting flanges of the 
motors to mark the holes for drilling. There's already some 
holes drilled into the T, and you may be able to use one or 
two as a starting point; you'll need to drill the others to 
match the motor mounting flange. 

After marking, use a center punch (the spring loaded 
kind is easiest) to indent a spot for drilling. The small 
dimple created by the punch helps prevent the drill bit from 
"skating" across the metal. 

For best results, use a drill press and clamp the T in a 
vise. (Avoid holding the T with your hands because if it's 
yanked loose during drilling, it could cause an injury). 

Place a block of soft wood (such as pine) behind the 
metai for support, and be sure to wear eye protection. Set 
the drill to slow speed to avoid overheating the bit. Add a 
drop of oil over the punched mark, and slowly drill through 
the metal. 

Drill a single hole — also using a 9/64" bit — near the 
bottom of the T stem for the skid. Do the same for this 
hole as above: mark with a center punch, add a drop of oil, 



FIGURE 4, Detail 
of the non-rotatins 
skid, composed 
of a ^32 x 1/2" 
machine screw, 
hex nut, and 
acorn (cap) nut 





















and drill slowly. Wipe off the oil when you're 
done drilling. 

Secure the motors using four 4-40 machine 
screws and nuts. The heads of the screws 
should be on the side of the motors; the nuts 
should be on the underside of the robot. 
Because the holes are somewhat oversized, you 
can use the slop to help align the motors. You 
want to make sure the wheels are as parallel as 
possible. 

Finally, construct the skid by threading a 6- 
32 hex nut onto a 6-32 x 1/2" machine screw. 
See Figure 4 for the assembly detail. Place the 
hex nut near the head of the screw. Insert the 
screw into the hole and fasten in place with a 6- 
32 acorn nut on the bottom side of the base. 
Tighten the hex nut against the T to secure the 
screw in place, 



Upgrading the Gearbox Maters 

The DC motors used in the Tamiya three-speed crank 
axle gearbox are designed for three volt operation, and they 
are relatively inefficient. They're fine if you plan on 
controlling your Mini T-Bot using switches or relays and a 
three volt battery pack, but they're not a good choice for 
electronic motor control. Powering them at the usual 4.5 to 
6 volts will shorten their life, plus require motor bridge 
circuitry capable of supporting three to four amps (yes, 
amps!) of current if the motor becomes stalled (it stops and 
won't move). 

The three-speed crank axle gearbox uses a Mabuchi FA- 
130 motor. The 130 size is common (it's popular in slot 
cars), and you can get replacement motors that are not 
only rated at higher voltages, but consume a lot less 
current. One such option is the 130-size motor offered by 
Pololu (their item #1117). It's rated at six volts, and has a 
stall current of only 800 mA. The price is under $2 per 
motor. 

The lower current motors not only consume less 
battery power, but allow the motor to be used with low 
cost H-bridge control circuitry. Suitable single chip solutions 
include the SN754410, though I prefer using a L298 as it 
provides a bit more functionality. (More about interfacing 
the Mini T-Bot to an L298 below,) 

Enhancing the Mini T-Bot 

There's no requirement that you design your Mini T-Bot 
with the same Tamiya three-speed crank axle gearbox 
motors and dollar store toy wheels. As an example, Figure 
5 shows an alternative design, using a collection of readily 
available Tamiya parts: 

* Tamiya #72004 worm gearmotors. These provide 
gear ratios of either 216:1 or 336:1, making the 
robot slow but strong. I usually select the 216:1 ratio 
when constructing small desktop bots. You need two 
motors. (The mounting flange spacing is the same as 



44 SERVO 06.2011 



on the three-speed crank axle 
gearbox,) 

• Tarniya #70145 narrow tire set These 
are 58 millimeters (about 2-1/4") in 
diameter, and securely attach to the 
round 4 mm axle shaft of the worm 
gearmotors. The wheels come in 
pairs, so you need just one set. 

• Tarniya #70144 ball caster. Use this 
instead of the static skid to provide a 
unidirectional caster. You can select 
any of four heights; when used with 
the above motors and wheels, pick 
the 16 mm height option. Drill either 
two or three holes for mounting the 
caster; the placement of the holes is 
somewhat critical as there is little 
room for error. You get two ball 
casters in the set, but you only need 
one. 

The worm gears use Mabuchi RE-260 
motors which (when operated at six volts) consume about 
3 amps of current if stalled. That's too much even for an 
L298, so if you go this route you'll want to consider using 
more robust H-bridge circuitry. 

Programming the Mini T-Bot 

With your Mini T-Bot constructed, you'll want to watch 
it scoot around the floor. Your options are virtually 




» • 



/ 







FIGURE 5, Alternative 
Mini T-Bot, using upgraded 
worm gearmotors, wheels, 
and ball caster. 




unlimited, but for demonstration purposes, I'll discuss some 
simple Arduino code you can use to run your Mini T-Bot 
through its paces. 

Remember that the standard Arduino cannot be 
directly connected to DC motors. You need to interface the 
motors to the Arduino through an H-bridge circuit, shield, 
or chip. Figure 6 shows a typical H-bridge module that 
supports the direction and control of two DC motors. 

For my prototype, I used a motor shield equipped with 



A Menagerie of Found Parts 



There are plenty of everyday objects you can use for robot 
building - all it takes is looking at them a bit differently. 
Here are some examples to whet your appetite: 

Plastic storage containers. Available in square, round, 
and other shapes, these durable plastic boxes — available in 
the housewares section of any department store — can be 
used with or without their press-on lid, Containers are 
available from small snack size to big shoeboxes. 

Plastic fishing tackle box. Wheels are mounted to the 
sides of the box; motors, batteries, and other critical 
components are placed inside. The box can be popped open 
to gain internal access. 

Small "dorm-size" trashcans. Just large enough to hold a 
Big Gulp, these trashcans have a convenient cylindrical shape 
and removable top. Great for building miniature R2-D2 bots. 

Computer mice* A discarded computer mouse makes a 
great body for a micro-miniature robot. Almost all mice can be 
disassembled by removing one or two screws on the bottom. 
Take out the innards and install small motors, a small battery, 
and a one-chip bra in . 

Compact discs and DVDs. Save the world's landfills and 
use these 4.7" diameter discs for robot bases. Use care when 
drilling holes in the plastic; the material can shatter into very 
sharp pieces. If you need added strength, sandwich two discs 
together. 



Sofderless breadboards. Solderless breadboards are 
used to experiment with circuits before using more permanent 
solder and wire-wrap construction. Mount motors and wheels 
on the underside of your solderless breadboard, and you 
create a versatile and ever<hangeable mobile robot 

Plastic project boxes. These boxes — sold by RadioShack 
and other electronics stores — are made to hold custom 
electronics projects. The boxes come with removable metal or 
plastic lids to allow access to the inside. The plastic is easily 
drilled for mounting stuff. 

Clear or colored display domes. Also called a hemisphere 
or half-round dome, display domes can be purchased in sizes 
from about 2" to over 12" in diameter. The dome can be used 
as the body of the robot, or as a cover to protect its 
electronics. A "robotic ball" can be made by gluing two domes 
together. 

PVC irrigation pipe. All forms of polygonal frames can be 
constructed using PVC irrigation pipe. Most hardware and 
plumber supply stores carry PVC pipe in various sizes and wall 
thicknesses. 

Hardwood laminated flooring samples. Already in about 
the right size and shape for a small bot, these samples are 
made by laminating a thin veneer over a sheet of high density 
board. Thickness is about 1/4". Cut off the tongue-and-groove 
edges used to assemble the wood to make flooring. Round off 
the corners to keep the wood from chipping. 



SERVO 06.2011 45 



5V 



Arduino 



AO 




A1 






> 


A2 


3 
(0 




& 


a;j 






J 




(.1 


A4 


C 






A5 



D13 
D12 
D11 
D10 
DQ 

oa 

D7 
D6 

Dfi 
D-1 
D3 
D2 

D' 
DO 



GND 



PWM 
?WM 
PWM 



PWM 



Motor 2 



. .v 



Motor 1 



1«* 




* Don'l yse just the L298 chip. If you are using discrete 
components instead of a module or shield you need lo 

aJso add flyback diodes to protect against back-EMF. 



FIGURE 6. Basic wiring diagram for connecting an 

Arduino microcontroller to an H-bridse module, When 

using a shield, the electricai contact between the Arduino 

and module is incorporated in the edge connectors. 



DC motor driver speed test 
Motor connected to 
digital pins 4&5 



/ 



const int Ml_Ctrl = 6; 
const int Ml_Dir - 7; 

void setup (} { 

pinMode (Ml_Ctrl , OUTPUT} ; 

pinMode (Ml_Dir, OUTPUT); 

digitalWrite(Ml„Dir, LOW); 
} 

void loopO { 

for(int i=96; i<=255; i + + ) 
analogWrite(Ml_Ctrl, i); 
delay (3 5) ? 



Listing 2 -PWM 
Motor Speed 
Control Demo. 



( 



analogWrite (Ml_Ctrl , 
delay (1000) ; 



0) 



//Set direction 



//Sweep speed from 

// 96 to 255 
//Delay 3 5ms 
// between changes 

//Turn motor full 

// off 

//Wait one second 



an L29S motor bridge IC. The shield I used is from DFRobot 
(available at Robotstore.com, among other online 

retailers). Another option is the DFRobot Romeo which 
combines an Arduino and the L298 shield in one unit. 

The shield includes the L298 chip itself, plus the 
necessary flyback diodes to protect the L29S from back- 
EMF produced by the motors. Power for the motors is 
separate from the power to the Arduino and the logic 
circuitry on the shield, 

(Note the addition of the 0.1 uF ceramic disc capacitors 

46 SERVO 06.2011 



DC motor driver test 

Motors connected to digital pins 

4&5 , and 6&7 



/ 



const int Ml„Ctrl = 6; 

const int Ml_Dir = 7; 
const int M2_Ctrl = 5; 
const int M2_Dir = 4; 

void setup { ) { 

pinMode (Ml_Ctrl, OUTPUT) 

pinMode (Ml_Dir, OUTPUT); 
pinMode (M2_Ct rl , OUTPUT) 
pinMode (M2_Dir , OUTPUT) \ 



//Set pin 
// assignments 



//All pins are 
/ / OUTPUTS 



) 



void loopO { 



robot_fwd ( } 
delay(3000) 



robot_rev( } ; 
delay (3000) ; 

robot„right ( } ; 
delay (3000) ; 

robot„left ( ) } 
delay (3000) ? 

robot„stop( } ; 

delay(1500) ; 



//Loop through motion 
// routines 



//Delay 3 seconds before 
/ / moving on 



listing 1 — Mini 
T-Bot Demo, 



) 



//Motion routines for forward, 
// spin right, spin left, and 
void robot_fwd() { 

digitalWrite(Ml_Dir, HIGH) ; 

digitalWrite(Ml_Ctrl, HIGH) ; 

digitalWrite(M2_Dir, LOW) ■ 

digitalWrite(M2_Ctrl, HIGH); 
} 

void robot_rev ( ) ( 

digitalWrite(Ml_Dir, LOW); 

digitalWrite(Ml_Ctrl, HIGH) ,- 

digitalWrite(M2_Dir, HIGH) ; 

digltalWrite(M2_Ctrl, HIGH) ; 
) 

void robot_left () { 

digitalWrite(Ml = Dir, LOW); 
digitalWrite(Ml_Ctrl, HIGH); 
digitalWrite(M2_Dir, LOW) ? 
digitalWrite(M2_Ctrl, HIGH); 
) 

void robot m right ( ) { 

digitalWrite(Ml_Dir, HIGH); 

digitalWrite(Ml_Ctrl, HIGH); 

digitalWrite(M2_Dir, HIGH); 

digitalWrite(M2_Ctrl, HIGH); 
} 

void robot_stop() { 

digitalWrite(Ml_Ctrl, LOW) ; 

digitalWrite(M2_Ctrl, LOW) ; 
} 



reverse, 
stop 



at the motors. For best results, solder these directly to the 
terminals on the motor. The capacitors help to suppress 
noise caused by the motors which can interfere with the 
proper functioning of the microcontroller.) 



There are a number of similar L298 
Arduino shields and stand-alone modules, 
and If you use one of these, just remember 
to adjust the I/O connections accordingly. 
On the DFRobot shield, the motors are 
connected to pins 4/5 and 6/7, Each motor 
uses two pins; one for direction and one for 
control. 

Listing 1 is a demo Arduino sketch that 
cycles through the basic functions of DC 
motor control for a robot: moving it forward 
and backward; steering it left or right; and 
stopping. 

The control pin for each motor can also 
be used with pulse width modulation (PWM) 
to set the speed of the motor. Listing 2 
shows how this is done using the Arduino's 
analogWrite statement. To set the speed of 
the motor, you specify a number from (off) 
to 255 (full on). These values control the 
duty cycle — the ratio between on and off 
times - of a fast series of pulses sent to the 
motor. 

Not all motors respond to very low duty cycles. 
When used with the Tamiya worm gearmotors, values 
under about 96 have little or no effect. That's why the 
for loop in Listing 2 starts at 96, and goes to 255. 

Important note! In programming code, the 
physical direction of a DC motor is ambiguous. It all 
depends on how the motor is wired to the control 
circuitry. I intentionally wired both motors in the exact 
same way to the L29S shield which then required that 
the motors be commanded in opposite — one motor is 
set to LOW, while the other is set to HIGH. This propels 
the bot forward or backward. If a motor doesn't turn in 
the direction you want it to, merely flip its wiring to the 
control circuit. 

Using Larger Ts for 
Larger Bats 

You're not limited to just the 6" T strap. By using a 
bigger T, you can construct a larger (and heftier) robot. 
For your reference, Table 1 are the specifications of the 
most commonly available sizes of Simpson Strong-Tie 
strapping Ts and their weight in ounces, 

Yikes! .., the 1212T strap weighs almost a pound, so 
you'll need bigger motors (and batteries) to haul that kind 
of weight around. 

The robot brute in Figure 7 uses a pair of 12" straps, 
separated by 5" long aluminum tubing used as risers. In this 
















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o v - / o 


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o ° 














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o o y 








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o 


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o 












o 






o 





o 


o 




O 





o 










o 


o 


o 




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o o 



o 

o 


o 
o 

o 















Model 


Material 


L 


H 


W* 


Weight 


66T 


14 gauge galvanized 


6" 


5" 


1-1/2" 


5 oz 


12ST 


14 gauge galvanized 


12" 


8" 


2 H 


11 oz 


1212T 


14 gauge galvanized 


12" 


12" 


2" 


14 oz 


TABLE 1. 

* Width is the width of the strapping metal. 



FIGURE 8. Outline shapes of three common nail plates. 
Like T straps, these are found in the lumber section of local 

hardware or home improvement stores. 

particular prototype, the motors were mounted at an angle, 
with the metal of the lower T bent at 45°, This was partly 
done to accommodate the motor itself, as its mounting 
holes were on the side opposite the axle and wheels. I also 

did it simply to be different. 

Other Sheet Metal for 
Lumber Strapping 

Don't stop with just T-shaped straps for building robot 
bodies. The same lumber section of your local home 
improvement store has plenty of other choices. Some of it 
is specially formed and bent for things like hanging 2x4 
joists in an attic or garage. These are somewhat less useful 
than flat metal. 

Figure 8 shows the outline drawing of three commonly 

SERVO 06.2011 47 



9 o 

o o 


s e. 


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ft 


a 




H 


o 




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o 



e a q g. o 



a a a a 



6 o e & a 



6 O O « 



o & e ?■ « 



* o e a 



O D O O O 



o 



FIGURE 9* Two of an almost unlimited number of ways to 
combine nail plates to construct robot bases of all shapes 
and sizes. 

available nail plates — so called because they're used to nail 
pieces of wood together. As with the T strap for the Mini 
T-Bot, these are made by Simpson. If you can't find this 
brand, there are other similar products out there. 

LSTA9 Strap Tie measures 9" x 1-1/4", Example uses 
include: a center rail in a walking robot; a connecting strap 



Learn 

Electronics 




Build 
of Kits 



Do 
Robotics 




GSSTechEd.com 
1-800-422-1100 




a a a a 

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6 & & 

□ 600 

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for wood, metal, or plastic bases; or a side angle bracket 
for tracked bases. 66L L Strap is an L-shaped plate that 
measures 6" on each side. If you need bigger, there's the 
88L which is 8" on each side. Example uses include: 
mounting brackets for larger robots or outriggers for 
motors. 

TP37 and similar Tie Plate is basically a flat plate with 
different lengths to suit various applications. The width 
for all sizes is 3-1/8". For the T35 length it's 5"; for the 
TP37 length it's 7", for the TP39 length it's 9". Example 
uses are: a robot base; a mounting plate for heavy parts 
(large motors, batteries) on framed robots; or side panels. 

Figure 9 shows how you might combine some of 
these sheet metal pieces to make various kinds of robotic 
bases. Or, you could use the LSTA9 as a cross piece for 
mounting motors or legs, or use it as a long side bracket 
for a tank style robot. 

You may elect to cut or trim some of the pieces, but 
since they're already in the basic shape you need, there is 
less work required overall. Sheet metal for lumber 
strapping is typically 18 or 20 gauge, and can be cut with 
a hacksaw, metal snips, or - my preference — electrical or 
air powered motorized shears. 

Of course, the concept of the no-cut extends beyond 
the Mini T-Bot or the other strapping products detailed 
here. You can use the same idea for other robot designs 
made with different metal materials, no matter where you 
find them. The key points to keep in mind are: 

• The material should already be in the size you need, 
so no cutting is required. 

• Avoid very thick materials for small robots, as they 
add unnecessary weight. 

• Consider sheet materials that can be bent to create 
unusual robot base shapes. Try a 6" x 12" aluminum 
sheet purchased at a local hobby shop. 

Keep Your Eyes Peeled and 
Your Tape Measure Out 

Before leaving the home improvement store, be sure to 
take one last stroll down the aisles. You'd be surprised 
what you'll find when you look at things from a robot 
builder's perspective. You never know what interesting 
tidbits you'll discover that can be the framework of your 
next robot. SV 



Gordon McComb is the author of 
Robot Builder's Bonanza, now in Its 
fourth edition. Greatly expanded 
and updated, this best selling book 
covers the latest trends in amateur 
robotics, and comes with 10 all 
new robot construction projects, 
plus more ideas for building 
robots from found parts. Look 
for Robot Builder's Bonanza, 
Ed in the SERVO Webstore at 
http://store.servomagazine.com Gordon 
may be reached at rbb@robotoid. 




48 SERVO 06.2011 



CPL 


Ds — Part 4 


complex programmable logic devices 


1 1 1 u n j t*! 1 1 jm 1 1 1 1 1 1 iTn 


by David A, Ward 



As we've mentioned in the previous articles in this series, HDL (or hardware 
description language) is really the preferred method used to program CPLDs 
versus the graphical or schematic method that has been demonstrated so far. 
(We've used the schematic method up to this point because it's an easier way 
to get started programming CPLDs. Now that you have a better idea of what a 
CPLD is and what it can do, it's time to introduce and begin using HDL. 



www.servomagazjne.com/index L php?/magazine/article/june2011_Ward 



f course, in a single magazine article we'll only be 
able to give a fairly brief introduction to HDL. There 
are many resources available online if you want to 
learn more about HDL. ! recommend The Low-Carb VHDL 
Tutorial by Bryan Mealy, This is a good and concise resource 
with many examples, HDL is also referred to as VHDL — the 
"V" stands for a very high speed integrated circuit. 
Although HDL may appear similar to some computer 
programming languages, the end results are quite different. 
When a computer language program is compiled, it is 
compiled into machine instructions that the microprocessor 
will execute one at a time in a sequential manner. When an 
HDL program is compiled, it is compiled into 
interconnections which will be configured into the CPLD. 
When the CPLD is programmed with these 
interconnections, the circuit will operate in a parallel or 
concurrent manner. So, the order in which HDL lines are 
entered into the HDL source code may not matter as far as 
the final operation of the circuit is concerned. HDL is really 
a description of a digital logic circuit rather than a set of 
sequential operations to be performed, such as in a 
computer program. 

HDL programs contain two main sections: the "entity" 
section and the "architecture" section. The entity section 
comes before the architecture section and declares the 
inputs and outputs of the digital logic circuit. The 
architecture section describes how those inputs and outputs 
from the entity section will behave in a digital logic manner. 
Figure 1 is an example HDL listing for a two input AND 
gate with inputs named A and B, and one output named X. 
As you examine the HDL listing, note a few things. First, 
HDL is not case sensitive, so that input "b" would be the 
same as input "B," HDL lines are terminated with a semi- 
colon (;). White space — extra spaces added for clarity — are 
also ignored by the compiler. You can add comments where 
you want after placing two dashes (— ); this means that the 



compiler does not attempt to compile anything after the 

two dashes. 

Let's take this simple HDL two input AND gate, compile 
it, and program it into a CPLD in the Xilinx Project 



entity firstHDL is 








Fort ( A : in 


STD 


LOGICS 




B : in 


STD 


LOGIC; 




X : out 


STD 


LOGIC) 




end firstHDL; 








architecture Behavioral 


of firstHDL is 


begin 








X <^ A AND B; 

end Behavioral; 








FIGURE 1. 





j ISE Project Navigator (M.70d) - C:\Users\WARD\Docu me nts\< 



File Edit View Project Source Process Tools V 



□ i*H 






X «o c* 



» 



Start 



Welcome to the ISE© Design Suite 

Project commands 




pen Example*., 



FIGURES. 



Recent projects 



Hiv-ii lUI.^ j-Vi^Lr f^i-i ^ ivni^j-± ir- W-**. U**t- U^lj^j.! l-j% nnr.r 



SERVO 06.2011 49 



Working Directory: C:VJsers\WARDpocument5VCPLD Artjdes\first 
Description; 



FIGURE 3. 



I 



Select tr 

Top^evel source tvpe: 



urce for the project 




* J — ■■ — T — £■*■ 



New Project Wizird 



FIGURES. 



Project Summary 

Project Navigator will create a new project with the folewing specifications. 



Project: 

Project Name: firstHDL 

Project Path; C:\User3\WARD\Docuiaents\CFLD Articles^ first 

Working Directory : C:\Users\WARD\. Document s\CPLD ArticleaN 

Description: 

Top Level Source Type: HDL 

Device : 

Device Family: XCS5GQXL CPLDs 

Device : kc 9 5 7 2 xl 

Package: PC44 

Speed: -10 



Synthesis Tool: XST ( VHDL /Veri log) 

Simulator: ISim (VHDL/Verilog) 

Preferred Language: VHDL 

Property Specification in Project File: 

Manual Compile Order: false 

VHDL Source Analysis Standard: VHDL- 53 



Store all values 



Message Filtering: disabled 




Family 
Device 
Package 
Speed 



XC9500XL CPLDs 

XC9572XL 

PC44 



-10 



Top-Level Source Type 

Synthesis Tool 

Simulator 

Preferred Lanquaqe 

Property Specification in Proje 

Manual Compile Order 

VHDL Source Analysis Standard 

Enable Message Filtering 



.: 



HDL 



XST (VHP L/Veriioqj 

g) 



FIGURE 4. 




n 



T_£_ 



New Source Wizard 



Select Source Type 

Select source type, file name and its location, 



FIGURE 7. 



Schematic 
=1 User Document 
Verilog Module 

!ffl^ure 



^1 s> ■ 



TP 1f "ni liliMj 



p] VHDL Package 
gj VHDL Test Bench 



File name: 



firstHDL 



Location : 



C;NUsers\WARD\PcH 



] ISE Project Navi 




-.WW^UIIUMMU 



Navigator, First, open the Xilinx program and from the start 
tab, select new project (see Figure 2). From the Create 
New Project window, locate and name your project, and at 
the bottom select HDL as the top-level source (see Figure 
3). In the Project Settings window, the CPLD information 
should be the same as in the past projects, however, make 
sure that the preferred language is set as 
VHDL (see Figure 4), Select finish from the 



Source Process Tools 



New Source... 



Source,.. 



£1 



J Add Copy of Source... 



Hierarchy 

B O xc9572> 

C Unc 



New VHDL Library... 

Manual Compile Order 

Import Custom Compile File List,.. 



The vie 
project 



Disable Hierarchy Repairing 
Force Hierarchy Reparse 



:o the 

roject 



^Articies\fir: Project Summary window as shown in 

Figure 5. You will now be taken back to the 
main ISE Project Navigator window, From 
here, select Project > New Source, as in 
Figure 6, From the Select Source Type 
window, select VHDL Module and give your 
file a name and location (see Figure 7). 

In the Define Module window, you can 
enter your port names and whether they're 
inputs or outputs. Or, you can simply click 
on next and fill this information into the 
entity section later {see Figure 8), 

Figure 9 is a summary window; select 
finish from here. You will now be taken 
into the HDL template that was created for 




50 SERVO 06,2011 



New Source Wizard 



fLYfirstHDLxise - [firstHDUhd] 



lelp 



Define Module 

Specify ports for module. 



FIGURE 8, 



Entity name fksti-O. 
ArchitKture name Behavioral 



Port Name 



Direction 



in 



in 



out 



in 



in 



in 
in 



* 



* 



Bus 

D 



D 



EL 

n 

□ 



Summary 

Project Navigator wilt create a new skeleton source 


with the following specif 


Add to Project: Yes 

Source Directory: C: Risers \WARDpocuments\CPLD Articles \firstHDL 

Source Type: VHDL Module 

Source Name: firstHDL vhd 

FIGURE 9. 

Entity name; firstHDL 

Architecture name; Behavioral 

Port Definitions: 

A Pin in 
B Pin wx 
X Pin out 



^* 



^ H 3 Qi 



*\? + e r 9 



18 
19 
20 
21 
22 
23 
24 
25 
2 6 
27 
28 
29 
30 
31 
32 
33 
34 

36 
37 

39 
40 
41 
42 



library IEEE; 

U3e IEEE. STD^LOGIC^l 164 .ALL; 

-- Unconsment the following library declarati 
-- arithmetic functions with Signed or Unsig 

— use IEEE. NUMERIC STD.ALL; 



-- UncoiETftent the following library dec 

-- any Xilinx primitives ir. tr.is code. 

— library UNISIM; 

— use UN2SIM.VCoirponents.all; 

entity firstHDL is 

Port ( A : in 3TD_LOGIC; 
B : in STD_LOGIC; 
X : out STD^LOGIC) ; 
end firstHDL; 

architecture Behavioral of firstHDL is 



.arati 



begin 



end Behavioral; 



: IGURE 10. 




you (Figure 10). 

Notice in the HDL template that the 
entity section is already completed for you, if 
you entered port names and directions from 
the earlier Define Module window; refer 
back to Figure 8. Notice also there are 
several lines of comments following two 
dashes which are green in color. The only 
real code or instructions that the compiler 
will use — other than the entity and 
architecture sections — are the library and 
use instructions on lines 20 and 21 . The 
architecture section, however, is not 
completed for you. 

Figure 11 shows the HDL code for the 
AND gate entered into the architecture 
section. From here on, everything is 
accomplished the same as it was when 
entering a schematic circuit. Select 
Implement Top Module (the green play icon) 
and if it compiles okay, you can go on into 
the Impact program and program your 
CPLD. If there are errors in your source code, 
error messages will be displayed in the 
console window at the bottom of the 
Navigator screen showing you which lines 
had problems. We won't go into all of the 
details how this is done here; you can refer 
back to Part 2 to see all of the steps to go 
through to compile and program a CPLD, 



34 
35 



3 : in STD_LC3rC; 

X : out STD_tC3I^); piqmre ^ 



36 end firstHDL; 

5; architect ure Behavioral of firstHDL is" 

39 

40 begin 

41 

42 X <= A AND 5; 

43 

end Behavioral; 
45 '""'" 



i^l 



C—*i-ir\i ,,Ux 



^L 



% 
% 


33 
34 
35 


PORT {A, 3 :IN 5TD_LOGIC; 

Q, R, 5, T, U, V, W ;OUT 3TD_ 
end HDL 3; 


:-:}; 


% 


36 
37 


architecture Behavioral of HDL 3 is 






38 










'cegir. ^^^ 








Q <^ A AND B; ^V 






f 41 


R <= A OR B; ^ 






42 


S <= A NAND B; 1 






43 


X <= A NOR B; 1 






L 44 


U <= A XOR B; J 
V <= A XNOR B; ^f 
H <= NOT A; M0r 


FIGURE 12. 




47 








48 


end Ber.ivicril; 





SERVO 06.2011 51 



*2 
33 
34 
35 
36 
37 
33 
39 
40 
41 
42 
43 
44 
45 
46 
47 
48 
J|9_ 



entity TRUTH_TABLE_1 is 

PORT {A, 8, C :IN STDLOGIC; 
X :OUT STD_LCGIC); 
end TROTH TABLE 1; 



-tirutli title aet-up 3 inputs 1 OCtejHK 



»j Set RTUTech Viewer Startup Mode 



architecture Behavioral of TRUTH_TA3LE_1 is 
SIGNAL BITS_IN : 3TD_LOGIC_VECTOB (0 TO 2>; 

begin 

BITS_IN <■ A £ a £ C; — concatenate the 3 inputs 

WITH BITS^IN SELECT 

x <- p o* when " :•:.", 

■1' WHEN "001", 
'0' when ":.:", 

'0* WHEN "Oil", 
'0' WHEN OTHERS; 
end Behavioral; 



FIGURE 13. 



32 


entity TROTH JT ABLE 2 is 


33 


PORT (A, B, C :IN 5TI>_LOGIC; — 3 inputs 


34 


DISPLAY I OUT INTEGER RMJGE TO 7) ; ^-tliiS Will generate 3 CTOtJJ 


35 


end TRUTH TABLE 2; 


36 




37 


architecture Behavioral of TRUTH TABLE 2 is 


38 


SIGNAL BITS IN ;STD LOGIC VECTOR (0 TO 2); 


39 


begin 


40 


BITS IN <™ A £ B £ C; —concatenate the 3 inptits together 


42 


KITH BITS IN SELECT 


43 


DISPLAY <= WHEN "ODD", 


44 


1 WHEN "OOl*, 


45 


2 WHEN "010", 


46 


3 WHEN "OH*, 


47 
43 


4 when "ioo% FIGURE 14. 

5 WHEN "1-jI", 


49 


6 WHEN »110*. 


an 


7 WttFJyl » 



vitw LonwridFiu Line i_uy run 

View HDL Instantiation Template 
User Constraints 





loorplanlO - Pre- Synthesis 
Implement Design 
£}© Synthesize - XST 



View RTL Schematic 



View Technology Schematic 
: k Syn tax 

£}0 Translate 
CXj Fit 



fi(j) Generate Programming File 
S -^ Configure Target De vice 

Start ^r| Design Files | Iff Libraries 



insole 



Launching Design 5 r JirjBary/ Report Vie 




SG Stc P 

Run With Current Data 



§► Implement Top Module 

Design Goals & *^***^« 

FIGURE 15- 



?£ Process Properties. 



F 



reate RTL Schematic 

5 Select items you (want on the schematic from the "Available Elements" list and move them to the "Selected Elements* list 

- Use the Filter control to filter the "Available Elements" list by name 
) Press the "Create Schematic" button to generate a schematic view usmg the items in the "Selected Elements" list 



Available Elements 
3 JV TfiUIHJABlEJ 






Inflected Elements 








■JL 


*«■> 


^ ft 




^ 6 




r **^ 


-i- C 


«-nm>itft j 


-*» K.cmp_e^00Ol 












- 


T 


FIGURE 17. 







3 



i 



2 mUTH.TMlE_l.vrid ' *"j Ci^tare^iUK'poMBeritsVJLD ArtdeitntLjrrCH jaftE_l\m_r-rtJ«Bl__S_r«rJ^t ton*tre*.Min § #* THtJlHJ*BUI_l OjR] 



~n S 



Select how the- RTL/ Tech Viewer behaves when It is initkalv invoked 

Startup mode 

•■ Start with the Explorer Wlrard 

Irt this mode, the Explorer Wizard is the initial: screen, end .(lows 
you to select the elements that you warm to see cvn the initial 
schematic 

start with a schematic of the top-level stock 

ft this mode, the Explorer Wizard is bypassed and an initial schematic 
is created with only the top-level block displayed- you can then use 
the log:, expansion capabilities of the Viewer to start expanding from 
the top-level Mode 

FIGURE 16. 

You can arso change- the startup mode by selecting Edrt-s-Ptefererrees under 
the RTL/TecJi Viewer page 



L 



:V.i Show this dialog on startup 



OK 



All of the other basic logic gate 
functions can be entered in the same way 
the AND gate was; refer to Figure 12 

One of the most common methods 
used to plan and design digital logic circuits 
is to use a truth table. Let's look at one way 
to enter truth table information into HDL 
code, (Figure 13). Let's look at what is 
taking place in this HDL listing. Line #32 
begins the entity section. Line #33 defines 
three inputs named A, B, and C, that are 
defined as STD_LOGIC types of inputs. Line 
#33 also illustrates how comments can be 
added after the HDL code using the two 
dashes. 

The inputs could also have been 
declared as BIT types ":IN BIT." A BIT type 
can either be a 'T or a '0', and nothing else. 
A STD_LOGIC type can be a T or a '0' or 
several other things, as well. A 5TD_LQGIC 
can also be a T (high impedance; a '-' 
(don't care); an 'X' (unknown); an 'L' (weak 
'0'), or an 'H' (weak '1'). When the Xilinx 
program sets up your HDL template, it 
usually defines the pins as STDJ.GGIC Line 
#34 declares an output named "X" as an 
STD^LOGIC type. 

Line #35 ends the entity section. Line 
#36 is white space which is ignored by the 
compiler. Line #37 begins the architecture 
section. Line #38 defines a locally used 
SIGNAL named BITSJN which will only be 
used in the architecture section. It sets up a 
three-bit STD_LOGlC_VECTOR which will be 
used to hold A, B, and C so they can be 
evaluated together rather than one at a 
time. Line #39 is the begin label which is 
necessary inside the architecture section, 

Line #40 concatenates the three inputs 
A, B, and C, and puts them into BITSJN so 
they can be evaluated together. Line #41 is 
white space. Line #42 sets up the WITH 
SELECT WHEN structure. Line #43 will make 
the output or X a when the three inputs 



52 SERVO 06.2011 



h*»JIWh, wsw A.vCHe ArW»UIWreH.TABL'..nI*uT£>H.TAW.l— . ■ rtttitujim^i CSTi*j 



m fTlMIH.TAHJf Jv*rf> 



^^i 



I'-kiii Mi thnfavi LjywM Hdp 
IW^QT/* <T £> & .- j ^-- - 



Hi 

.1 T; i- !i 



LU>«3 



Oatfn Ot-rnX. of TTHmi_T*aii.i 



IW 



are all 0. Lines #44 through #46 list the 
other conditions of the truth table and what 
X will be with each condition of A, B f and C. 
By the way, the order of A, B, and C in 
relation to the three 0s to the right of the 
word WHEN is the same. That is, A is the 
left 0, B is the center 0, and C is the right 0. 

Line #47 "WHEN OTHERS" can be used 
if you want all of the other truth table 
outputs to be the same and do not wish to 
list every possible input condition. Note, 
however, that the WHEN OTHERS statement 
is still necessary even if you do list all of the 
possible input combinations. Line #48 ends 
the architecture section. 

Notice the use of single quotes for the 
ones and zeroes before the WHEN, and the 
use of the double quotes after the WHEN in 
lines #43 through #47. Notice also the use 
of a comma after lines #43 through #46 and 
a semi-colon at the end of line #47, Not 
having these commas, quotes, and semi- 
colons in the right places will cause errors 
when attempting to compile the code. 

Let's now look at entering a truth table 
that has three inputs and three outputs into 
HDL. Check out Figure 14. Notice in line 
#34 there will be an output named DISPLAY 
that has an integer range of to 7. This will 
automatically set up three output bits 
named DISPLAYO, DISPLAYS >, and 
DISPLAY<2>. If you put other numbers in the 
range such as to 10, for example, the 
compiler will set up four outputs since it will 
take four bits to place values up to 10 out of 
the circuit, Notice in lines #43 through #51 
that the output values are decimal and are 
not enclosed in any type of quotes. 

Other than that, the code listing looks 
the same as the single output code shown 
earlier. Of course, you can do many more 
things with HDL than just these two truth 
table examples. Being able to enter truth 
table information into HDL will get you a 
solid start into using HDL, 

Let's look at a couple of other things 
that the Xilinx software can do at this time. 
One thing you can do is generate a 
schematic diagram from HDL code and vice 
versa. To generate a schematic from HDL 
code, select Implement Design > Synthesize - XST > View 
RTL Schematic > left-click then right-click, and from the 
drop-down menu select Run (see Figure 15). From the next 
window, make sure the Start the Explorer Wizard radio 
button is selected and then select OK (see Figure 16). From 
the Create RTL Schematic window, select ail signals > Add > 
and then Create Schematic, as shown in Figure 17. You will 
now see the schematic diagram that was generated from 
your HDL source code in Figure 18. To turn a schematic 



fi V * 



s*i:? 



FIGURE 18. 




3"* 



:*lt± I'.I'IJIH i*4£t .• FTifil JOPfcFc'hC 



Ingr: 



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P- (J HDPraeoiEi Running 

X 



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i y Dnign UtStki 

Otv.t 'SchenjiJc tymbol 
View Com mind tine Log f-rie 
tj Ch«;V Design ftufes 

JH VRwHDLFwKt'ramlMpdfl 
3 View HDL Instantiatian Template 

*y User Conitfiints 

(i Smplemtnt Deign 



% 



^- 



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_Ul_ 



2* 

25 
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3i 
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35 
36 

if 

33 
39 
40 
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41 
46 
49 
50 
51 



use leee.suttMle^sid.JUJ.; 



FIGURE 20. 



eiLiiv ana_2 xn 

poet ( I t U 
B : in 
C : in 

X : a-.it 
csd and 2? 



stdJLoeic; 

sid^logic; 



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itt^t;-? KKJf¥P5 = JtfjiBg : 
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end ea^aitenc; 



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stdJLoflicij 
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diagram into an HDL code listing, select Design Utilities > 
View HDL Functional Model > left-click then right-click, and 
from the drop-down menu select Run (see Figure 19). You 

will now see the HDL code listing generated from that 
schematic diagram (Figure 2.0). 

The final article next month will use a CPLD to control 
a mobile robotics platform to follow a dark tape line on a 
table-top. This will tie all of the principles that have been 
introduced in these articles together. SV 

SERVO 06.2011 53 



Make Your Robot's 

Wires Extinct 

by Fred Eady 

Way back when dinosaurs roamed the hills of Tennessee, I was learning how to wire 
up tube and transistor circuits. There was no such thing as ExpressPCB. In fact, there 
was no such thing as a BBS or the Internet. Only the professional magazine writers of 
the day with access to a printed circuit board house could muster an article that 
included a project mounted on a fancy copper clad piece of fiberglass. Meanwhile, I 
continued to string wire between circuit points and electrically seal them with solder. 

Years passed. The dinosaurs died. Dial-up BBS sites gave way to the Internet and 
professional printed circuit board houses reached out to folks like you and me. 
Telephones lost their wires and personal computer Ethernet cables disappeared. 
I'll bet you're still wired to that microcontroller that you're going to use to control 
that rolling aluminum slab you call a robot. Read on and I'll show you how to lose 
the wires. 

www.servomagazi ne.com/index. php?/magazine/artiele/june2Q11_Eady 






A Mew 8051-based Powerhouse 

Before we put on our pointy hats and discuss the 
radios, I'm going to introduce you to the SPECTRUM ACE 
2a — a really neat, self-contained computing platform from 
121 Controls. ACE is short for Advanced Control 
Environment. The SPECTRUM ACE 2a single board 
computer is going to be right down your alley. As a robot 



FIGURE 1. Some 
things work so 
very well that they 
never need to 
change. This is the 
same circuit I cut 
my 8048 and 8051 
teeth on 25 or so 
years ago. 



DS89C45Q 



ADO 


7 


1P 
2D 
3D 
40 
5D 
6D 
7D 

ao 

LE 
OE 


1Q 
2Q 
3Q 

4Q 
5Q 
6Q 
7Q 

8Q 


id 


AO 


AD1 


3 


1ft 


A1 


AD2 


4 


17 


A2 


A03 


R 


1fi 


A3 


A04 


fi 


1fi 


A4 


ADS 


7 


14 


AS 


ADS 


a 


13 


A3 


AD7 


fl 


1? 


A7 


ALE 


11 








1 











128KxSSRAM 



74HC573 



74HC20 




head, you are ALL about control, and that's what the 
SPECTRUM ACE 2a is designed to do. 

The ACE 2a is the largest microcontroller platform in 
the SPECTRUM ACE family. The ACE 2a is based on the 
Dallas Semiconductor DSS9C450 ultra high speed Flash 
microcontroller If you roamed with the dinosaurs, you 
know all about the 8051 microcontroller and its variants. 
The DS89C450 microcontroller does in one clock cycle what 

the T-Rex 8051 does in 12 clock 
cycles. 

Remember the 8751 ? The 8751 
had EPROM under quartz that could 
be electrically programmed and 
erased via a UV lamp. If you had a 
few days between spins, you could 
set your programmed 8751 in the 
sunlight and eventually somewhat 
erase the program memory area. I 
used to keep opaque tabs to cover 
the quartz window to prevent 
accidental erasure of my 8751 code 
that took days (and sometimes 
weeks) to perfect. Not so with the 
DS89C450 microcontroller. Like just 
about every modern microcontroller, 
the DS89C450 keeps your magic 
potion safe in 32K of eight-bit Flash. 
The DS89C450 doesn't stray far 
from the things that make it a true 



«MEMORY ENABLE / I/O SELECT 



OxFOOO-OxFfFF 

0xF200-0xF3FF~ 

0xF4Q0-0xF5FF- 

0x F5O0-0xF7FF~ 

OxFaOO-OxFSFF- 

OxFAOO-OxFBFF 

OxFC'OEOxFDFF 

OxFEOO-faFFFF 



54 SERVO 06.2011 



S051 descendent. For instance, the classic 74HC573 data 
latch and 74HC138 memory decoder circuitry you see in 
Figure 1 is utilized in the SPECTRUM ACE 2a hardware. In 
the old days, we had to hang our external SRAM out on 
these address markers as the stock 8051 only supported 
128 bytes of SRAM on chip. I recall that the 2K x 8 61 16 
SRAM was one of my favorites. The ACE 2a still hangs 
SRAM out on the address decoders. However, instead of 
a paltry 2K of SRAM, the ACE 2a puts clothespins on 
128Kof eight-bit SRAM. 

Every well-heeled robot can deduce the time of day. 
Thus, any cousin of Robby is endowed with an electronic 
clock of some kind. The ACE 2a design includes a Dallas 
Semiconductor DS28DG02 real time clock. In addition to 
providing a battery-backed RTCC function, the real time 
clock also brings some general-purpose I/O lines to the 
party. 

Although you may think digital rules, we actually live 
in an analog world. To help you and your intelligent 
bucket of bolts cope, the ACE 2a is equipped with a 
Dallas Semiconductor 1-Wire DS2450S 1-Wire quad 
analog-to-digital converter (ADC). 

Stepping back and pondering the power of that 
collection of electronic components under the Canon in 
Photo 1, you realize that the ACE 2a gives you full access 
to the CPU data bus, the low order address bus, and an 
octet of 512-byte memory-mapped I/O chip selects 
spanning a 4K block. If we were to total up these 
goodies, the list would include: 



oooooooooooooooooooooooooooooo 









MS 




■H 1 nl nPh 1 1 J m^ m 




fjhujntlulujM-MW 







^•tiiittti 



■ -A. J*; ^*. 



-■■+•■■ "* rrv < n .h. •.'--.. — v. -i: — ■•: .- ro U a - - ■- . 

o o o.o.o o oo o o o o.o oo oo.o oo o o o o 



PHOTO 1. Back then, I would have slain old T-Rex myself to have 

access to this technology. Programming an 8051 is like playing a 

Fender Telecaster through a Fender tube amp. Good vibes. 



89<iftatll «.* * «• # e » 



siKtiitumuii 



V«r B.91 . 



1WEIVM001 

FCC ID ABCWMtQOX 
MAC B0190EA001&6 



mc 






B0Z.11W9 

Made in Taiwan 



i-^iiitlififfffitftf 



-i * 9 • • • • • • m ee «»••.• 



DS2450S 1-Wire A-to-D 

Six Hardware Interrupts 

Two Full-Duplex 1 15K baud UARTs 

One PWM (Software Generated) 

1 General-Purpose I/O Lines 

32K of eight-bit Flash 

128K of eight-bit SRAM 

Reset Button 

+5 VDC Power Supply 



As my mom would say in a slurpy Southern drawl, 
"That's nice." What she really means is, "So What?" 
Somebody's got to write drivers for all of those "features." 
Usually, that somebody is you. 

Not this time. The console portal of the ACE 2a provides 
you access to ALEC. ALEC is smart, but it is not of our 
world. ALEC is short for Advanced Language for Embedded 
Control. ALEC is SPECTRUM ACE 2a standard equipment. 
Everything necessary to implement and drive that 
aforementioned list of features is part of ALEC. ALEC don't 
need no stinkin' compiler. ALEC don't need no stinkin' 
hardware programmer. Your programs can be written, 
edited, debugged, and executed via ALEC and a simple R5- 
232 portal, which is part of the SPECTRUM ACE 2a, 

TX, RX, and GIUD in an 
Ethernet Sort of Way 

There are a number of radio modules that we could 



PHOTO 2. The i WE M- 1001 is an ultra low power consumption 
802.1 Ib/g Wi-Fi module that sports a basic three-wire 

UART interface. 



use to eliminate that wire that connects your 
microcontroller's UART to a console, However, we're going 
to cut the wire in such a way as to allow you to access your 
mechanical animal using Internet protocols that look like a 
standard three-wire RS-232 hookup. 

Photo 2 is a top-side shot of the Atech iWEM-1001 
ultra low power wireless embedded module. The iWEM- 
1 001 is an 802.1 1 b/g device that can operate at 54 Mbps. 
Our iWEM-1001 is equipped with an embedded chip 
antenna. It can also be had with a standard UFL/SMA 
antenna connector. If your microcontroller has a UART, 
you're ready to rock as the iWEM-1001 only requires a 
simple three-wire serial connection. It supports standard 
baud rates between 2400 bps and 1 15200 bps. 

The iWEM-1001 is actually a fully functional Wi-Fi radio 
station. Its chip antenna feeds an embedded 32-bit CPU 
that is running an operating system and a network stack. A 
sequence of "+++" sent from a terminal emulator such as 
HyperTerminal Or Tera Term Pro forces the iWEM-1001 from 
data mode to command mode. Once in command mode, 
the iWEM-1001's configuration can be viewed or set. Data 
mode exposes its business end. Sending the word "exit" to 
the iWEM-1001 module via the terminal emulator 
terminates command mode and forces its module into data 
mode. When the iWEM-1001 is powered up, it enters data 

SERVO 06.2011 55 




PHOTO 3. What you see here is the iWEM-1001's LD1 1 17A 3.3 

volt LDO voltage regulator circuitry and a SP385E true +3V or +5.0 
volt RS-232 line driver/ receiver. 



mode by default. If configured to do so, as soon as its 
internal CPU boots the module attempts to associate with a 
WLAN network. The iWEM-1001 can associate via DHCP or 
static network addressing. Once it finds a friendly WLAN, it 
can converse with other network nodes via TCP/IP, UDP, 
ARP, and ICMP as a client or server. 

The serial side of our three-wire to Internet protocol 
bridge is facing the camera lens in Photo 3 

A Sipex 3S5E RS-232 line driver/receiver acts as the 
gateway to the iWEM-1001's Internet protocol engine. The 
Sipex 385E can operate with power supplies of either +3 
volts or +5 volts. As far as power supply voltage is 
concerned, the iWEM-1001's operational range is 2.4 VDC 
to 3.7 VDC. SO, an LD1 1 17AL33 LDO voltage regulator with 
a fixed output voltage of 3.3 VDC is holding court on the 
serial side of the iWEM-1 001. 

Setting Up the iWEM-1001 

The iWEM-1001 command set consists of three 
command types. Action commands execute network 
functions. For instance, an action command exists for 
scanning, connecting, and disconnecting from the network. 
Configuration commands ultimately load the iWEM-1001 



i£ IWLW lfti: C'JttJ-fl 



Flush Timeout: ID 



CMD 

> get_state 

Baud: 19200 mtu: 14O0 

mac: 0O:i9:0e:a0:01:56 

rtiLAN Utocte: (Infrastructure} 

ssid: edtp channel : ii - Authed, Assoc'ed 

TX Rate 34Mbit/s- Autorate 1 

302,11 Up 

IP: 192.168.0,112 NM: 1 55 .255 .255 .0 GW: 192.163.0 

Host IP: 192. 16$. 0.1 Remote port: 2000 Protocol: 



* Fr* fcft* Cirtid Wnkwt 



1 Local Port: 1000 

2 Ctcp server} 



SCREENSHOT 1. The content of this capture provides 

iWEM-1001 configuration information, as well as the results 

of the DHCP process. 



and network configuration information into the 1WEM- 
1001's Flash memory. Configuration information must be 
saved using the save command in order to be updated and 
used following the next iWEM-1001 boot. Configuration 
commands act on the iWEM-1001 hardware and the 
network. For example, the $et_baud_rate 19200 command 
sets the iWEM-1001 baud rate to 19200 bps. The network 
command set_protocoi 2 instructs the iWEM-1001 to act as 
a TCP server. Status commands allow the user to view the 
current state of the iWEM-1001's hardware and network 
settings. The status of the iWEM-1001 from a network 
point of view Is also available by issuing the get_state 
command. The best way to get a grip on the iWEM-1001's 
command mode command set is to walk through setting 
up an iWEM-1001. 

There are a few things we need to know before we 
can put the Wi-Fi side of the iWEM-1001 to work. Some of 
those things are obvious, such as the type of antenna it's 
fitted with. Photo 2 tells us a chip antenna is installed. 
Issuing the set_antenna 1 configuration command informs 
the iWEM-1001 that it will be receiving and transmitting 
using an embedded chip antenna. Here's some known 
information about the network our iWEM-1001 will 
participate in: 



SSID 

802.11b/g Channel 
Network Type 
WEP Key Number 
WEP Key 



EDTP 

11 

Infrastructure 

1 

112233445566778899AABBCCDD 



We can use WLAN-oriented configuration commands to 
enter our network information: 



set_ssid EDTP 
set_channel 11 
set_wlan_mode 
set_passwd wepl04 1 



1122 3 344556677 8 8 99AABBCCDD 



The SSID and channel match the associated 
configuration entries of the router that is in charge of our 
wireless network. At first glance, issuing the 
set_wlan_mode command is not necessary as our 
network type is infrastructure (uses an access point or 
router) and infrastructure (0) is the default network type. 
However, we would have to get up on our donkey and 
proclaim that this particular iWEM-1001 has never 
been configured before. I don't like riding the 
donkey. We'll make sure the iWEM-1001's network 
type is configured as infrastructure. If you're 
wondering where the WEP key number falls into all 
of this, it is the first argument of the set_passwd 
wep104 command. If WEP is not your idea of 
security, the iWEM-1001 is also capable of securing 
the network using WPA {56t_pa5$wd wpa 
<pas5Word>). With our iWEM-1001 WLAN 
configuration complete, we can move on to the 
network configuration, Here's what we know: 



DHCP 
Protocol 



Enabled 
TCP Server 



56 SERVO 06.2011 




Connection Description 



New Connection 



Enter a name and choose an icon for Jhe connection: 

Name: 
IWEM19200WINSOCK 



Icon: 




OK 



SCREENSHOT 2. We're going to configure 

HyperTerminal to use an Ethernet interface instead 
of a serial interface. 



That doesn't seem 
like much, but using 
DHCP eliminates us 
from having to know 
the IP address 
particulars- The DHCP 
process will supply the 
iWEM-1001 with its IP 
address, the gateway IF 
address, and the 
netmask. The default 
TCP server local port Is 
1000. Since we aren't 
depending on another 
application to call the 
port numbers for us, 
the defaults for local 
and remote ports will 
work just fine here. 
So, we have a pair of 
network commands to enter: 

set_dhcp 1 
set_protocol 2 



It would be nice if we initially configure the iWEM-1001 
UART's baud rate to match the console speed of the 
SPECTRUM ACE 2a: 

set_baud_rate 192 00 

That's all we need to do. There are a total of three 
UART configuration commands. We'll take the defaults on 
the packet size and flush timeout values as the default 
packet size is the maximum value of 1400, and the flush 
timeout value of 10 mS is plenty of cushion at 19200 bps. 
Save is an action command and if we want to keep our 
configuration entries, we had better issue it. 

In that I was able to snap Screenshot 1, we definitely 
nailed the UART configuration. Let's peruse Screenshot 1 
and see how we did everywhere else. I tapped in "+++" 
into a 19200 bps Tera Term Pro session and as you can 
see, CMD and a command prompt were sent to the 
terminal emulator by the iWEM-1001 indicating that it has 
entered command mode. I issued the status command 
get_state to display the current thoughts of the iWEM- 
1001. 

Recall that we configured the 19200 bps baud rate 
and left the MTU and flush timeout values to the 
discretion of the iWEM-1001 hardware. If you've read any 
of my Ethernet discussions or attended any of my 
Microchip MASTERS classes, you know that every Ethernet 
device that plans On participating in Internet activity must 
have a unique MAC address. Note that we did not have a 
configuration entry for a MAC address. That's because the 
MAC address was issued to Atech by the IEEE, We did 
have a say concerning the WLAN mode, as we chose to be 
safe rather than sitting on our donkey feeling sorry. 

The SSID and channel were configured to make sure 



Cancel 



1 Connect To 




'?IX 


Enter details for 
Host adoVess: 
Port number; 

Connect using: 


92QOWINSOCK 

the host that you want to call: 




192.168.0.112 








1000 








TCP/IP (Winsock) 


&i 






_ ■ 
OK 


Cancel 









SCREE NSHOT 3. The combination of an IP 

address and port number results in a TCP socket. 

Our iWEM-1001 TCP socket happens to be a 

server socket that listens for incoming requests 

from clients. 



that the iWEM-1001 associated with the router in the lab 
and one in a neighboring building. Everything went as 
planned as the iWEM-1001 was authenticated by our router 

and permitted to associate with the EDTP network. The TX 




PHOTO 4. The Li-fon battery pack I've chosen to use is powerful 

enough to support the iWEM-1001 for a long time at full power. 

However, the iWEM-1001 is designed to sleep and conserve battery 

life. So, a less juicy battery configuration can be substituted. 

SERVO 06.2011 57 



IWEM-19200 WINSOCK Properties 



0® 



Connect To Sellings 



& 



Function, arrow, and cttl keys act as 

© Terminal keys Windows keys 



Backspace key sends 

Drt+H O Del O Ctrl+H, Space, Qrl+H 



Emulation; 



VT100 



Teiminal Setup, 



Tetnet tesrninal ID: 



vnoo 



Back scroll buffer lines: 500 



t 



f~l Play sound when connecting or disconnecting 



Input Translation... AS C 1 1 S etup 



OK 



Cancel 



IWEM1?7PCr-WIK$QCK Hype [Terminal 






EHHI 



121 Controls Inc. (C) 19307010 - Beta W.01 
Software Licensed frost Davis-Clark Inc. 2910 
SPECTRUM ACE 128K BUILD 91.16 2010/10/21 



>HilN HI 
>_ 



SCREENSHOT 5. We are now 

connected to the SPECTRUM ACE 
2a via a TCP socket. 



i 



Connected (JitS* 



vTiOO 



TCP/IP 



HUN 



:•!,->-' r! ' PiWf 



SCREENSHOT 4. The VT100 is one of the greatest terminals 
of ail time. Everybody that is anybody in the terminal emulator 

business emulates this terminal or one of its many variants. 



Wth i9W'W<M5«K < ilyprr]«rmm#l 



nt EJH «M CJ Turner help 

Dei , S OS eff 



ami 



121 Controls Inc. (C) 1996 2010 Beta VI. 91 
Software Licensed frost Day is-C lark Inc. ?010 
SPECTRUM ACE 128K BUILD 01.10 2010/19/21 



>Ra« *l 

H0 ald(i) 

>29 delai/( 19909) 

530 p, "Current teup-", 

>40 o. u5ing(HHtt,HKald(a < 9,»7.G29e-3 

>S0 jump 20 

> 

> 



SCREENSHOT 6. 1 used the 

HyperTerminal Send Text File function 
to load this little program over the 
TCP socket connection. 



UttAttWUU^ttM 



Fig Edt *** Cfll TrintfGr Hcfc 



>20 cklnydl'irjIJlJ) 

>30 p. "Current temp-", 

>40 p. using(HttH.tt) >fl ld(a,0)"7.629e~3 

>50 jump 29 

> 

>mn 

Compiling Code. . . . 



Executing. . . . 



Current 
Current 
Curren t 
Current 
Current 
Current 



tewp- 
tenp- 
tenp- 
tenp- 
temp- 
tcrtp- 



n 8 

12 f 
72.7 
72. e 

7? . t 
72.7 



Stop - In Line 29 

29 delay (10090) 

>Rair #1 
> 



SCREENSHOT 7. ALEC and the 
SPECTRUM ACE 2a are like peanut 

butter and jelly. 



Qct**at4o.<rt'j9 



VTSCO 



r.-?> 



.:.-:>-, *-<, 



rate is the result of taking the default values in the WLAN 
data rate configuration. 

The 802.1 1 up indicator is supported by the iWEM- 
1 001's DHCP-assigned IP address of 192.168.0.1 12. The 
DHCP process also provided the network mask value of 
255.255.255.0. The IP address of the GW (gateway) is 
actually the IP address of the router. The GW IP address is 
also provided courtesy of DHCP. 

At this point, there are no external applications 
calling themselves host. The iWEM-1001 only knows 
about one host, which happens to be the router. 
The local and remote ports are at their default 
values and the iWEM-1001 is running its built-in TCP 
server application. As soon as I enter "exit," DATA 
will replace CMD and the iWEM-1001 will become a 
serial to Ethernet bridge. 

System Integration 



The point behind this discussion is to allow the 
SPECTRUM ACE 2a console port to be accessed 
from anywhere. The iWEM-1001 hookup is simple 
and easy. As you can see in Photo 4, the iWEM- 
1001 is powered by a 3.7 volt 6,600 mAh Li-Ion 
battery pack. The serial connection between the 
ACE 2a and iWEM-1001 is a no-brainer TX-RX-GND 
setup. 

The ACE 2a works best with a 1 9200 
HyperTerminal VT100 session. So, let's configure a 
HyperTerminal WINSOCK emulator session 
beginning with Sereenshot 2. Instead of the 
normal serial interface, we're going to configure 
HyperTerminal to use an Ethernet interface. 

We know that the iWEM-1001 was leased an 
IP address of 192.168.0.112 by the router on the 
EDTP network. We also know that the iWEM- 
1 001's local port is 1000, The combination of its IP 
address and local port form a TCP socket. A TCP 
socket is not more than a communication 
endpoint. In this case, our TCP socket is a server 
socket that listens on port 1000 for incoming 



iqastfrq 



58 SERVO 06.2011 



requests from clients. We define our TCP socket to 
HyperTerminal as shown in Screenshot 3, 

At this point, we can connect to the i WE M- 1001. Once 
connected, we must select Properties from the File drop- 
down menu and select the Settings tab as shown in 
Screenshot 4. This is where we define the terminal 
emulation type- The ACE 2a wants to see a VT100 and 
that's what we'll appear to be. A tap of the spacebar 
results in Screenshot 5 which is the ACE 2a banner We 
have successfully contacted the ACE 2a via a TCP socket. 



System Test 



I wrote a small ALEC test program 
and loaded it in Screenshot 6. The 
ALEC code sets up the ACE 2a's A-to-D 
subsystem in line 10. A delay is 
honored in line 20. Lines 30 and 40 
push the current temperature to the 
ACE 2a's console. The temperature 
data originates from an LM34. Upon 
entering "run" into the HyperTerminal 
TCP socket session, ALEC compiles and 
executes the temperature test 
program. 

Screenshot 7 is the result of 
contacting the ACE 2a console, 
loading a program, executing a 
program, and viewing the results via a 
wireless TCP socket connection. 

The Possibilities 

Besides telling me why it's chilly in 
here, this little demonstration can also 
be used to tell me why it's chilly in 
Idaho, TCP sockets work on the 
Internet just like they do in a lab 
network contained within the confines 
of a single room. All you have to do to 
put the ACE 2a on the internet is use 
a routable address and designate a 
local port address. The 192.xxx.xxx.xxx 



Fred Eady can be reached via 
email atfred@edtp.com. 



Sources 



IWEM-1001 

Lemos International 

ww w. le m os i nt.com 

SPECTRUM ACE 2a 

[2 1 Controls 

www.i2icontrols.com 

Li-Ion Battery Pack 

Tenergy Corporation 

www.tenergybattery.com 



IP address range is not routable on the Internet. However, 
you can use the 192.xxx.xxx.xxx address range in your 
network behind the router. Most of today's routers employ 
NAT (Network Address Translation) functionality which 
allows you to literally punch a hole in the router to allow 
outside access to devices on the router's 192.xxx.xxx.xxx 
network. For instance, to put our iWEM-1001 configuration 
On the Internet, we would use the router's NAT 
functionality to open an Internet access portal to TCP 
socket 192.168.0.112:1000. 

Whether you want to cut the wires locally via a LAN or 
internationally via the Internet, the iWEM-1001 is a 
foolproof and inexpensive way to go. SV 



■ 




FUN DA MENTALS *» m. D.oinn.r 

Need the Basics? 

Follow along with our nriti of article* wtiiclt InCludaa 

M«y to nndflrxtAnd graphic*. 
Si art Ins in tho May 2010 iitug. 



-E+ 



Subscribe Today! (■ 



npUnnil iJtpllMl \ 

L r-> i.u vi nn i if / 







Visit www.nMtavoHg.com or call (800) 783-4624 




SERVO 06.2011 59 



Programming The 

LEGD NXT: 

An Alternative Approach 

Suitable For Developing 

Tomorrow's Engineers 

by John Blankenship and Samuel Mishal 

No one makes building a robot easier than LEGO, and now, programming the LEGO 
NXT can be just as easy. The open-source LegoLibrary.bas described here makes it 
easy to introduce programming concepts to those new to robotics. Including the 
library in your RobotBASIC programs enables them to directly control the robot 
without downloading any programs to the NXT. This easy-to-use system creates an 
alternative motivational environment ideal for cultivating tomorrow's engineers. 

www.servomagazine.com/index.php?/magazine/article/june2011_Blankenship 



□ ne of the most important things robot enthusiasts 
can do is share their love of robotics with young 
hobbyists who may be destined to create the next 

generation of intelligent machines. Instilling aspirations of 




building a robot though, is simply not enough. Learning to 
program a robot should be the ultimate goal for students 
because programming promotes logical thinking and 
develops problem-solving skills. What is needed is a robot 
that is easy to build and easy to program. 

As mentioned, no one makes building a 
robot easier than LEGO. With their system, 
anyone can snap together a robot base and 
power it with modular motors. A variety of 
sensors can be interfaced by simply 
connecting them to the LEGO processor 
with a cable. The visual programming 
language that ships with the NXT robot was 
selected to make programming easy, but 
many users find procedural languages more 
intuitive. 

One advantage of a visual programming 
environment is that the programmer does 
not have to deal with the complexities of 
implementing flow control structures such as 
loops and decision statements. This can 
make visual programming very efficient for 
experienced programmers. Unfortunately, 
removing the complexities can also prevent 
some beginning programmers from truly 
understanding the logic of what is 



60 SERVO 06.2011 



happening. If you want proof of this assertion, watch 
children learn to program with a visual language. They 
generally can create programs quickly by simply duplicating 
pictures, but ask them to modify the program to create an 
alternative behavior and watch their reaction. 

It is important to stress that we are not saying that 
visual languages are without value. For many situations, 
they provide an ideal solution and visual learners may learn 
better when using them. 

Procedural languages, though, make the flow of the 
program much easier to grasp for many conventional users. 
Regrettably, though, procedural languages generally force 
programmers to immerse themselves in many other details 
in order to accomplish even simple tasks. In order to 
remedy this problem, we created a library of routines that 
hide the details of controlling LEGO's motors and reading 
their sensors. 

The library routines are generic enough that they can 
be used with a variety of configurations of the NXT robot. 
Figure 1 shows the robot we used to develop and test the 
routines. The LEGO computer has built-in Bluetooth 
hardware and a communication protocol that our routines 
use to control the robot directly without downloading any 
programs to the robot itself. This feature alone makes it far 
easier for many beginners to program the LEGO robot. (See 
this month's The NXT Big Thing column.) 

Let's look at a simple program that demonstrates how 
the library can make programming an NXT easy, but more 
importantly, it demonstrates how programs written with the 
library are easily understood by beginners. The program in 
Figure 2 is written in RobotBASIC — a free language 
available from www.RobotBASIC.com. 

The first line in the program includes the LegoLibrary, 
so that our routines become a part of the program. The 
second line initializes a variable to the number of the 
Bluetooth port used by our machine. The third line initializes 
the library and brings us to the main body of the program. 

A call to the library routine LegoDrive Motors turns 
both motors on at a FAST speed. The first parameter 
controls the left wheel and the second controls the right. 
The next line calls another library routine to produce a 
3,000 ms pause before the motors are 
turned off. Nearly anyone can quickly 
understand how this program works, and 
once told they can use a speed of SLOW 
as well as FAST, they can easily make 
the robot move at different speeds for 
different periods of time. They can also 
make the robot turn by stopping or 
slowing down one wheel while the other 
moves at a FAST pace. This open-loop 
control allows novice hobbyists or even 
children to program a robot to move in 
various patterns. We have successfully 
taught fifth graders the fundamentals of 
programming using this approach. 

After a little practice with open-loop 
control, It is easy to use LEGO's sensors 
to control the robot's behavior. The 
program in Figure 3, for example, 



#include "LegoLibrary .bas H 




BluetoothPort = 34 


FIGURE E. 


call Legolnit (BluetoothPort ) 




call LegoDriveMotors {FAST, FAST) 




call Wait [3000} 




call LegoDriveMotors (STOP, STOP) 




end 





causes the robot to move forward until the ultrasonic 
ranging sensor detects an object less than five inches away. 
When this happens, the robot turns a random amount and 
continues the behavior. 

Our LegoLibrary contains routines for interrogating 
LEGO's line sensor, sound sensor, bumper sensor, as well as 
the ranging sensor. The routines must be past the port 
number where the sensor is connected. This allows the 
utilization of multiple sensors if you choose. For example, 
you could create a robot with four ranging sensors. 

The source code for the library can be downloaded 
from www.RobotBASIC.com and anyone with 
programming experience can easily identify all the available 
routines by looking through the listing. Those new to 
programming might benefit from the book RobotBASiC 
Projects for the LEGO NXT. It uses the library routines to 
develop robot behaviors for avoiding objects, following 
lines, hugging walls, and more, 

A LegoSimulationLibrary is also available from the web 
page. When it is included instead of the standard library, 
the same programs control a simulated robot allowing 
experimentation even when hardware is not available. This 
can be especially valuable for schools because every student 
can work with their own simulated robot. When their 
program is working, the teacher can plug in a Bluetooth 
adapter to allow control of the real robot. 

If you are looking for a more conventional language to 
control your LEGO NXT or if you just want to share your 
enthusiasm with someone totally new to robotics, give our 
LegoLibrary a try. SV 



FIGURE 3 



# include "LegoLibrary .bas" 
BluetoothPort = 34 
RangePort = 3 

call Legolnit (BluetoothPort) 
call LegoRangelnit (RangePort ) 
while true 
call LegoRangeSensor (RangePort, r) 

// Places the distance measured into the variable r 
if r < 5 

call LegoDriveMotors [SLOW, -SLOW) 
call Wait (1500 + random(SOO) ) // 
else 

call LegoDriveMotors (SLOW, SLOW) 
endi£ 
wend 
end 



// rotate robot 
for a random time 



SERVO 06.2011 61 




The NXT 
Big Thing 

#11 




In Contrail 



By Greg Intermaggio 




Hey, hey, hey, 

everybody! Welcome to 

this edition of The NXT 

Big Thing that'll end with 

you using a remote to 

control Eddie! This 

month, we'll be learning 

how to make two NXTs 

communicate over 

Bluetooth, so that one 

can control the other. 




r~~ i rrrra d cm rr^i cm i—n c. 



62 SERVO 06.2011 




cm J — ; s—n 



oooooo 



www.servomagazine.com/iridex.plip7/magazine/article/june2011_lntermaggio 



Get ready to get busy, as we learn just how much 
programming has to go into both the remote control and 
the robot itself to make it go. 



NXT Prep 



We'll need two things before we get started 
programming: 

- A fully-built Eddie 2.0; you can find Eddie 2.0 building 
instructions in the January '1 1 edition. 

- A second, plain NXT with a touch sensor attached. 
Plug it into port 1 and attach it to the NXT any way 

you like. 



Understanding The Program 

As I said before, there are two components going into 
this project. 

The first component is the remote control. It takes your 
input from pressing buttons, translates it into something 
Eddie can read, and sends it to him over Bluetooth. 

The second component is Eddie, Eddie listens for the 
messages from the controller, and uses the variables sent to 
it to determine whether or not to move, and which 
direction to move in. 

Figure A shows the flow of information in a bit more 
detail. 



Control 



Figure A, 



Eddie 




* Interprets user input 

* Translates input into 
useable variables 

* Sends variables to 
Eddie via Bluetooth 





* listens for bluetooth 
data from control 

* Uses "Stop" variable 
to control stops 

* Ises "Steer" variable 
to control steering 




Writing The Cantral Program 



Now that we understand how the programs work, let's start by writing the program for the remote control. 



Cantral Test Program Instructions 



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Figure 1. Start by creating a new program called 
BT_ControLTest Then, click Edit > Manage Variables. 
Add a logic variable called STOP, and a number variable 
called Steer Stop will control whether Eddie moves or stops. 
Steer will control which direction Eddie moves. 



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Figure 2. Add a loop. Inside the loop, drag a touch sensor 

block in. Add a variable block and choose the Stop variable. 

Set the variable to write instead of read. Finally, wire the 

output of the touch sensor block to the input of the variable 

block. This means that when the touch sensor is pressed, Stop 

will be set to true. 




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SERVO 06.2011 63 



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Figure 3* Add three switches set to "NXT Buttons 11 for the 
sensor. Set the first switch to the left arrow; the second 
to the right arrow; and the third to the Enter button. 



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Figure 5, Add the same Steer variable block to the right NXT 
button switch- This time, set it to -100 for a full right turn. 



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Figure 7, Add a variable block to the end of the program and 
set it to the Steer variable. Next, find and add a Send Message 
biock to the end of the program from the Actions menu. Set the 
connection number to 1, the message to logic, and the mailbox 
to 1. Wire the value from the variable block to the number data 
hub on the Send Message block, You'll have to connect the two 
NXTs via Bluetooth manually, at which point you choose the 
connection number. The mailbox number is where the data is 
sent, and we'll use it Jater to tell Eddie where to look for those 
important variables. 



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Figure 4. Add a variable block to the side of the left arrow 

switch where the button is pressed. Set that block to the 

variable Steer and set it to write. Finally, set the value to 100. 

Recall that "steering" can be controlled by an integer between 

-100 and 100; -100 is a full right turn (it's reversed from a full left 

turn since Eddie has a gear train); 100 is a full left turn. When 

the left arrow is pressed, we'll ultimately want Eddie to turn left. 



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Figure 6, Again, add the Steer variable block to the Enter 
button switch. This time, set it to to make Eddie go straight 

forward when the Enter button is pressed. 



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Figure 8. Add a variable block and set it to the Stop variable. 

Add another Send Message block, and this time set it to 

connection port 1, message "Number," and mailbox 2. Then, 

connect the value from the variable block to the logic data hub 

on the Send Message block. 




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64 SERVO 06.2011 



Writing EdriiE's Program 

We're halfway there! Now, we just need to program Eddie to understand the Bluetooth messages. 

Bat TEst Program Instructions 



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Figure 1. Create a new program called BT_Bot_Test. Define a 
number variable called Steer and a logic variable called Stop 
these are the same variables from the Control program. 



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Figure 2. Add a loop. Inside the loop, add a Receive Message 
block from the Sensors tab. Set the mailbox to 1 and set it to 
the Number Out data hub to write to a Steer variable block. 



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Figure 3, Repeat the same process as Step 2, but set the 
mailbox to 2 and the variable to Stop. Wire the Logic Out data 
hub to the Stop variable. 



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Figure 5* If "Stop" is set to true (meaning the touch sensor is 
beins pressed), we want Eddie to stop moving. Add a Move 
block set to Stop on the true side of the logic switch. 




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Figure 4. Add a Stop variable block set to read and wire it to a 

switch set to logic. This will allow us to make Eddie react 

differently if the touch sensor is being pressed (meaning "Stop" 

is set to "true") than if the touch sensor isn't being pressed 

(meaning "Stop" is set to "false"). 



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Figure d. Add a Steer variable block to the false side of the 

logic switch. 





SERVO 06.2011 65 



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Figure 7. Add a Move block, and wire the output of the Steer 
variable to the Steering data hub of the Move block. 



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Figure 8, Finally add a Wait For Time block at the very end of 
the program, setting it for .1 seconds. This will make sure that 
Eddie doesn't try to look for Bluetooth sisnals too fast, when 

they aren't there yet. 



Finishing Touches 



So close! It's time to download our programs and 
configure our Bluetooth. Here's how: 

• Download BT_Control_Test to the controller 

• Download BT_Bot_Test to Eddie. 

• Access the main menus on both NXTs, 

• Go to Bluetooth and make sure both NXTs have 
Bluetooth both On and Visible. 




66 SERVO 06.2011 



• On one NXT, select Search from the Bluetooth menu. 
When the other NXT shows up in the search results, 
select it and connect. 

• Now both devices are connected. If either one is 
turned off, you'll have to re-establish the connection 
by going into Bluetooth > My Contacts, and selecting 
the other NXT, 

• Run the control program on the remote control, and 
the bot program on Eddie, 

If all goes well, pressing the orange Enter button on 
the controller should make Eddie move forward; either 
arrow should make him turn in the specified direction; and 
holding the touch sensor should make him stop in place 
until it's released. 



Wrapping Up 



We just learned how to connect two NXTs via 
Bluetooth, and make one act as a remote control for the 
other. In the next edition of The NXT Big Thing, we'll take 
Bluetooth control even further — so stay tuned! 

In the meantime, here's a few cool challenge ideas for 
you to keep your brain in gear: 

• Make Eddie's remote use a variety of sensors instead 
of the NXT buttons. 

• Program Eddie to play a sound when a certain 
sensor/button is used. 

• Attach a wireless camera, and have Eddie bring in 
your newspaper. SV 



Greg "LEGO" Intermaggio lives in the Bay 
Area, CA, where he runs a business 
called Techsplosion, bringing hands-on 
science to all ages and walks of life. In 
his spare time, Greg likes to unicycle, 
juggle, unicycle juggle, and battle killer 
robots! More information about Greg can 
be found at lnternnaggio.com. More 
information about Techsplosion can be 

found at Techsplosion.org 




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1 




*4j 





Tfiis month, we have the pleasure of presenting the 
Cross-Link Control System from Cross The Road 
Electronics. Cross The Road — founded by FIRST Team 
#217 mentors Mike Copioli and Omar Zrien — aims to offer 
a control system ideal for the competitive robotics 
environment by providing an accessible and expandable 
system based on the Controller Area Network (CAN) 
protocol most often seen in automobiles. It just so 
happened that we had the perfect platform on which to 
test out the Cross-Link control system - Protobot, a project 
from our FIRST days of yore that has made the occasional 
appearance in our column (see the May '09 issue for an 
earlier brain transplant). 

Cross The Road makes the bold claim that the Cross- 
Link system can be 
implemented by a user 
of any programming 
background, and that 
it can be used with 
any operating system 
and any programming 
language. Such broad 
applicability is meant 
to entice programming 
veterans, as well as 
novices. Finding the 
balance between 
accessibility and 
expandability is a 
difficult task, and one 
that is all the more 
critical in a competitive 



Ethernet 1 



Ethernet 2 



www.crossthcroadclectronicscom 




v^ 



The 2CAN Ethernet 

TO CAN GATEWAY, 



robotics setting where team members may come and go, 
and roboticists of all skill levels need to be accommodated. 
And, just in case that balancing act isn't overtly exciting 
enough, the Cross The Road team also offers the 
uCANDrive app which allows users to configure and drive 
their Cross-Link robot over their Android smartphone. 

Yes We CAN 

The Cross-Link control system is comprised of three 
main components. The first of those is the 2CAN, an 
Ethernet to CAN gateway that allows your computer to 
communicate with the rest of the CAN modules in the 
system. The versatile Ethernet connection also allows users 
to implement any processor or tool suite with the Cross-Link 
system. The compact module includes two Ethernet 
connections, a CAN connection, and wires ready to be 
outfitted with the connector of your choice. 

The other core member of the Cross-Link menagerie is 
the CANipede Robot Control Module (RCM). The CANipede 
has all of the inputs and outputs characteristic of a robot 
controller — including eight PWM channels, eight analog 
inputs, four digital l/Os, eight solenoid channels, four 
quadrature encoder channels, four relay outputs, and two 
CAN connectors. The CANipede includes two sockets for 
CAN connectors and a power cable with wires, once again 
waiting for the perfect connector for your unique project. 

Even though a centipede doesn't necessarily conjure up 
imagery of hardiness, the CANipede has the robustness to 
match the CAN protocol. All of the inputs and outputs are 
short circuit protected. This will probably be a lifesaver for 
many teams, because as much as you try to avoid drilling 



70 SERVO 06.2011 



www.servomagazine.com/index,php?/magazine/artic]e/june2011_TwinTweaks V/hy DtdThe Robot CrossTHe Rood? 








The TRENDnet Travel Router. 



any new holes after the 
electronics have been placed, 
we know that the vagaries of 
fate may compel some last 
minute modifications- With the 
CANipede's short circuit 
protection, accidentally bridging 
some pins won't kill your robot, 
and the problem is even 
helpfully identified by the 
hardware LED status light. 

The last major component 
of the Cross-Link control system 
is a portable wireless router 
from TRENDnet. The portable 
router operates on the 802,1 1 n 
wireless standard, and it comes 
with an Ethernet cable, a USB 
power cable, and a wall power source, 

A lot of folks have probably heard of CAN in the 
automotive context, where is has been the standard 
protocol since the 1980s. CAN is the standard in part 
because it is so effective in high noise environments. Cars 
put electronic equipment in close proximity to a noisy 
engine. Another realm that pits sensitive electronics close to 
noisy motors is competitive robotics which is one reason 
why the 2CAN and CANipede were developed. The Cross- 
Link system also aims to strike the balance between 
accessibility and expandability, and the first step in testing 
that balance would be to implement the system on an 
appropriate platform. 

Our aforementioned Protobot was an ideal platform. 
Protobot was constructed in 2004 by Team #1079 from 
leftover parts from our FIRST kits from 2003 and 2004 (for 
more on Team #1079's 2004 season, you can dig deep into 
the SERVO archives for the September through December 
'04 issues). Using the baste frame pieces, two CIM motors, 
and a serious gear train, Protobot is a six-wheeled robot 
with two drive wheels. With a complete electrical skeleton 
including a power distribution block and a set of Victor 
884s, Protobot would be a perfect way to test out the 
Cross-Link control system. 

All of the software and documentation can be 
downloaded from the easily navigable Cross the Road 
website (www.crosstheroadelectronics.com). The 
documentation includes manuals for each individual 
component, schematics, and a manual for the 
implementation of the Cross-Link system: as a whole. The 
only software required to implement the system is the CAN 
Firmware Utility, used to update the firmware of the 2CAN 
and CANipede, and the Robot Control Software (RCS) — a 
graphical interface that allows the user to control the robot 
over their computer. 



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The Roaming Drone 



The Cross-Link manual for the most part gives 



meticulous instructions on how to implement the control 
system — the first 10 pages are spent introducing the 
components of the system and walking you through the 
installation of the software. Such detailed instructions make 
the initial setup of the RCS fairly straightforward. One of 
the only brain ticklers that arose during the physical 
implementation of the system was sorting out the power 
requirements. 

All components of the control system need 
independent power, because power is not transferred along 
the CAN or Ethernet cables. The 2CAN and CANipede 
modules are flexible, and will take power between 6.5 and 
24V at 500 mA, The odd mod out is the TRENDnet router 
which demands nothing higher than 5.1 V at 1 A. For FIRST 
teams looking for a project in the off-season, meeting these 
power requirements is a simple affair. The power 
distribution board from distributor AndyMark will supply 
12V and 5V (and 24V, for that matter) from a battery like 
the one supplied in the FIRST kit of parts. 

Protobot was made from FIRST parts from the 2004 
season, and the power distribution block will simply source 
1 2V with spots for breakers from our 1 2V battery. This met 
the requirements for the 2CAN and the CANipede, but we 




Everybody loves Protobot! 



SERVO 06.2011 71 



TwiN Twenifs ... 




had to get a little creative to power the TRENDnet router. 
The solution was a simple voltage regulator circuit using a 
7805 \C and a couple of capacitors. Because of the strict 
warnings that came with the router that any voltage over 
5.1V could cause irreparable damage, we thought it best to 
check our circuit with the infinitely useful multimeter before 
hooking everything together. Sure enough, the regulated 
voltage was in the Goldilocks zone with an output of 
5,028V. We couldn't have gotten a better deal had the 
Priceline negotiator advised us that we could name our own 
voltage! 

Physically wiring up the components was 
straightforward. The 2CAN and CANipede come with free 
wires that were easily crimped into the sockets necessary to 
connect to the power distribution block. The TRENDnet 
router comes with a USB power cable that allows the unit 
to be powered from the USB port on a computer. We cut 
the end of the cable that attached to the router and 
extended the wires on the other side, so they could 
comfortably accommodate the required sockets. The 
compact components were easily mounted on an 
electronics shelf on Protobot, and a few strategically placed 
strips of Velcro were able to keep everything sitting tight. 

The manual sagely suggests a bench test to make sure 
everything is communicating properly. The first step is to 
make sure that the 2CAN and the CANipede have updated 
firmware which can be done with the 2CAM Firmware 
Utility. The Firmware Utility has a fairly self-explanatory user 
interface that gives helpful feedback as you go through the 
steps of establishing communication with the 2CAN. The 
only part of this process that was a hassle was synching the 
IP address of the computer with the 2CAN. The Firmware 
Utility ostensibly gives you a way to change the IP address 
of your computer through the utility itself, but the changes 
never seemed to take to our computer. Thankfully, the 
manual also walks users through how to change the IP 
address of their computer manually, which worked like a 
charm. 

After updating the 2CAN, you can open the Web 
Dashboard to update the CANipede. The Web Dashboard 
can be used to get helpful feedback from the entire control 
system, with the CANipede being just one possible node. 
Other nodes can be easily wired in parallel, but initial 
implementation of the system does not require anything so 
involved. Our only caveat about loading the firmware is to 
be cognizant of the jumper on the CANipede. The jumper 
can set the CANipede to termination resistor or bootloader 
mode. For the purpose of updating the firmware, make 
sure the CANipede is in bootloader mode. 

After updating the firmware, the robot is ready for the 
first bench test. The bench test uses the RCS to activate a 
solenoid switch. No actual solenoids were harmed (or used) 
in the making of this bench test, because the CANipede has 
LEDs that light up when each solenoid switch is activated. 
Using a USB game controller like the dual joystick model 
from Logitech is recommended. We didn't have one on 
hand, but they can picked up at your local electronics store 



72 SERVO 06.2011 



Why Did The Robot Cross The Road? 



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for only about $15. 

Mapping the controls to the Logitech 
controller is very easy, because all you have 
to do is navigate through a few drop-down 
menus. The RCS is even accommodating to 
those without fancy USB controllers, because 
you can set the inputs to be buttons and 
sliders that will appear onscreen. 

We were very happy with Protobot's 
new control system. The controls were a 
breeze to map to the game controller, and 
we were soon driving Protobot around our 
driveway just like in the glory days of yore. 
The handheld game controller is a lot more 
manageable than the controller boards we 
built for our FIRST robots, and the RCS was 
constantly giving helpful feedback like the 
robot voltage and a graphical meter that 
tracked our input via the joystick. The various 
buttons and triggers on the game controller 
also provided ample opportunities to manipulate any 
mechanisms that could possibly go on a FIRST robot. 

To The Victor, Go The Jaguars 



The system worked well and we were happy with our 
sleek game controller, but one area for improvement 
jumped out at us. One of the cool aspects of the Cross-Link 
control system was the advantages associated with the 
CAN protocol. Those advantages of noise immunity were 
not exploited to their full potential, because the entire 
system was not on the CAN network. The biggest 
exclusions were our Victor speed controllers which used 
noise susceptible PWM signals. This was quite the 
disappointment, because fine motor control could be 
potentially disrupted by a noisy robot. 

The disappointment, however, was easily remedied. 
Even though the scrappy Victor 884 will always have a 
place in our hearts (and our combat robots), a newcomer 
has pounced onto the scene that promises to take full 
advantage of the CAN protocol offered by the Cross-Link 
control system. The feisty newcomer is the MDL-BDC24 
Black Jaguar from Texas Instruments. 

The Jaguar is a motor controller designed specifically 
for the FIRST competition — something for use in harsh, 
high noise environments while still being accessible to 
newcomers. The Jaguar was a part of the 201 1 FIRST kit of 
parts, so the competitive environment and accessibility of 
the unit already seemed like a perfect fit for the Cross-Link 
control system. 

Even more perfect is the fact that the Jaguar includes a 
CAN interface. This means it can be incorporated seamlessly 
into the Cross-Link system while maintaining the noise 
immunity of a CAN network. The only caveat we have 
about the impressive Jaguars is that they are quite a bit 
bigger than Victor 884s, but they still fit perfectly onto 
Protobot's accommodating frame. 



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Cool Factor Engineering 

We have always been big fans of the cooE factor. The 
cool factor can take a variety of forms. It may be a 

completely nonfunctional embellishment, like whimsical 
decals or a paint job. It may be functional, but perhaps 




SERVO 06.2011 73 



TwiN Twenirs ... 




Jaguars to help Protobot really purr 
(not that Jaguar!), 




Android + Protobot = Awesome! 



overdone to the point of hyperbole (like putting a large 
3/4" thick 7075 aluminum plate on the front of your FIRST 
robot). The cool factor is anything that you can add to your 
project that will make people look at it and spontaneously 
utter "that's cool." Whatever form it takes, we think the 
cool factor is, in fact, an important part of any robotics 
endeavor. The cool factor helps people take ownership of 
the project. It gives them something to be proud of. Of 
course, any functional robot truly is something to be proud 
of, but a functional robot emblazoned with your own 
personality is something that cultivates a real sense of 

74 SERVO 06.2011 



personal accomplishment. 

The folks at Cross The Road Electronics apparently feel 
the same way about the cool factor as we do, because in 
addition to the workhorse-like user interface of the RCS, 
users can drive their robot through the uCAN Drive app for 
the Android smartphone. The uCANDrive app — which can 
be downloaded for free from the Cross The Road website 
or the Android app market — comes with five modes that 
allow for a broad range of control using joysticks, buttons, 
sliders, and even control for an onboard accelerometer. 
Setting up the uCANDrive is very similar to the setup with 
the RCS, and the wide array of possible buttons and sliders 
would be more than enough to control even the most 
intricate FIRST robot. 

Using the Android touch screen to control the robot 
makes you feel like some sort of mechanical maestro 
manipulating the spatial operating interface from Minority 
Report. And much like a skilled maestro, users do maintain 
a degree of control over the sleek interface with the ability 
to map outputs and modify scaling and dead bands. 

Controlling the robot with a flick of a finger on the 
Android touch screen was undeniably fun. The controls 
were responsive, and the sleek smartphone was even more 
compact than the USB game controller The Android also 
had the advantage of being the wireless access point itself 
— the USB controller still needed to be hooked into a 
computer, but the driver could follow their robot around 
with the Android all day. 

Far from being a gimmick, we think the uCANDrive app 
is a great way to demonstrate to students, in particular, the 
power of programming, the excitement of integrating 
technologies, and that their Android can, in fact, be used 
for something more important than Angry Birds. 

When Control Systems 
Compete, You Win! 

Reviving Protobot gave us an idea for the perfect 

application for a control system like Cross-Link. We built 
Protobot in 2004, after the 2004 FIRST season and in 
preparation for the 2005 season. Our FIRST team was at a 
crossroads. After two solid seasons, the original team 
members had only one more year before graduation, New 
members were coming in, but we needed a way to impart 
the enthusiasm that we had built up through two years of 
competition. That enthusiasm was at a critical mass after 
the 2004 competition, with the team brimming with ideas 
for next year and eager for a system on which to test them 
out. We built Protobot as a way to test new ideas and 
demystify the robot building process for new members. 

This sort of project would be a perfect opportunity to 
implement something like the Cross-Link control system. We 
think it's a great idea to have more choices when it comes 
to control systems for a robot, particularly in an 
environment like FIRST (or any competitive robotics, for that 
matter). Choosing between different control systems 
demands that teams understand what exactly makes those 



Why Did The Robot CrossThe Road? 



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systems different. Since a major 
difference here is the protocol, the 
simple availability of the CANipede 
RCM is a fantastic teaching 
moment on that core concept. The 
simplicity of implementing the 
Cross-Link control system is also a 
great way to achieve a major goal 
of a robotics team in transition: 
instilling confidence in the new 
team members. 

One of our biggest challenges 
when recruiting new team 
members was to convince those 
with no experience that they too 
could build a robot. Getting 
acquainted with the components of 
the Cross-Link system and removing 
the additional intimidator of 
programming is a great way to 
demonstrate that robots are not an 
inscrutable collection of wires and circuit boards, but rather 
a logical structure of electronics. The depth of the system 
also allows veterans to sharpen their programming skills or 
add a variety of mechanisms with the assurance that they'll 
be able to control them with the tap of a button or 
manipulation of a slider. 

Intrepid programmers have a lot to look forward to 
with the Cross Link RCS, because the entire project is open 
source. The code is all available online, and can easily be 
modified with an IDE like MPLAB. The inputs and outputs 
of the CANipede can be retooled, and the RCS interface 
can be modified. The 2CAN is the only closed source 
component of the system, but that shouldn't be too 
discouraging. 

Future versions of the 2CAN firmware will even allow 
users to add their own custom web pages to supplement or 
take the place of the Web Dashboard, The entire Cross-Link 
system — which can be obtained through trusted FIRST 
distributor AndyMark — costs $399.99, which should be 
well within reach even for smaller FIRST teams and other 
competitive roboticists. 

The folks at Cross the Road Electronics envision a 



RecoMMe^DeD weesiTe© 



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www, a ndy mark, com 

http://code.300gle.eom/p/crossfink-rcs 



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system that welcomes new family members every year. 

With an inner circle that already includes the 2CAN, 
CANipede, and friends like the Jaguar, we can only imagine 
how new additions would exponentially increase the 
possibilities of the Cross-Link control system. 



speO^ THINKS To 



Mike Copioli from 



omes. 



Andy Baker from AndyMark for the purr-feet Jaguars. 
Paul Copioli from VEX for the infinitely useful Victors. 



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SERVO 06.2011 75 





■D 

C 




NEW APPROACHES TO 
ROBOTICS EDUCATION 



b y 



Tom 



I I 



At the end of March, I decided to go to the Autodesk Oregon Regional FIRST Robotics Competition 
in Portland to observe, photograph, and help out in any way I could. I've always enjoyed robotics 
competitions over the past few decades, most starting out with just a few competitors and some basic 
rules. FIRST— For inspiration and Recognition of Science and Technology — started out the same way 
in a high school gym in Manchester, NH in 1991 and was (and still is) the brainchild of innovator Dean 
Kamen and MIT professor, Woodie Flowers, Before delving into the modern FIRST competitions, Td like 
to go back a few decades to those classes at MIT, Professor Flowers, and the innovative student rivalry 
that started it all. 



MIT Found a Better Way 

Most of us have had a college professor who just 
seemed to use a better method to teach. Instead of a 
boring spiel that could have been presented by a tape 
recorder, he or she had that special talent of 
being able to tune into what the students 
were thinking and was able to present 
course material in a most unique way. I had 
such a professor who taught anatomy and 
physiology — the absolute hardest class that 
I'd ever taken, but the most interesting, by 
far. 

I remember to this day, many of the 
most obscure details of the body, organ 
function and structure, and numerous Latin 
names of all the bones in our bodies- I think 
that's pretty amazing for a person who 
ended up in aerospace, robotics, and RF 
systems, and had nothing to do with 
medicine or human physiology. This 
learning/retention was not because I was an 
amazing student. I give credit to this one 
professor because he taught in a way that 
made me and my classmates want to learn. 




FIGURE 1. Woodie Flowers 



Putting Mettle to 
the Metal 

MIT Professor Woodie Flowers (Figure 1) is one of 

those amazing teachers. He taught the Mechanical 

76 SERVO 06.2011 



Engineering course, "Introduction to Design" back in the 
1970's; it was recently renamed to "Introduction to Design 
and Manufacturing." This was a hands-on class; not one 
with a professor who droned on as the students nodded 
off. It was an amazing success and was the seed for 

contests to come later. 

The original syllabus for Flowers' course 
specified as a final assignment "Design and 
build a robotic system for putting a round 
peg in a square hole, while a competitor 
tries to put another peg into the same 
hole." Not only did the student have to 
design a pretty robust robotic system, the 
student was in a competition with other 
students — always an exciting plus. 
Students received a box of materials that 
included two motors, various sprockets, 
cords, cardboard tubes, cardboard, and 
even some rubber bands. Unlike a simple 
term paper that some educators might 
request, Woodie had his students put 
'mettle to the metal' and produce a working 
robot. He then had them compete with 
fellow student's machines. Like the anatomy 
and physiology course that 1 took years 
back, this course was not an easy A, but the 
students loved it. 

After the students had formed teams and completed 
their individual robots, they took their creations to the on- 
campus Johnson Athletic Center, One would think it was 
some sort of rock concert turned athletic event inside as 



New Approaches To Robotics Education 



hundreds of students packed the center, with foot stomping, 
clapping, and cheering for various entrants as they clawed 
their way to various goals with balls or blocks in their maw. 

At the final competition, cheers rang out for the most 
outrageous robot or even the most spectacular failure. The 
major difference in this competition was that the entrants 
were not the students, but their robotic creations, These 
events were, however, much more noteworthy iconic classics 
that typified what has made MIT a world-renown institution 
of basic and advanced science and engineering. A scene 
from the 2008 competition is shown in Figure 2. 

The rules and goals changed each year, as well as the 
type of robot that each team constructed. These 
competitions became so noteworthy that they were 
frequently televised over network and public television 
stations. Other schools and universities soon learned that 
using robotic devices not only taught the many facets of 
engineering in a hands-on manner, but the competitive 
aspect honed the individual student's ability to work within 
a team to achieve the goal of the particular contest. 

Since 1970, Flowers' hands-on course has taught 
gracious professionalism and has inspired many students to 
go into the engineering field as first-rate engineers in 
companies across the nation. No field of science course 
would be complete without the accompanying lab sessions. 
However, labs in the past followed a rigid outline geared to 
the textbook. This innovative approach has now been 
adopted by many universities with a similar strategy in 
teaching technical subjects. 

Worcester Polytechnic Institute's 
Robotics Curriculum 

Earlier this year, I participated in an online NextGen 
Education and Research Robotics Virtual Summit presented 
by Robotics Trends' Virtual Conference Series, Among the 
many presenters who gave some very interesting talks and 
the virtual booths who shared some interesting approaches 
to education, there was a talk and booth by Worcester 
Polytechnic Institute (WPI) in Massachusetts. Technical and 
community colleges have offered courses in factory robot 
implementation, maintenance, and operation for a number 
of years. MIT, Stanford, and Carnegie Mellon, as well as 
many other universities have long had courses leading to 
advanced degrees in mechanical, computer, and electrical 
engineering with strong emphasis upon robotics. However, 
there are few actual degrees in robotics or robotics 
engineering. 

WPI feels that their series of Robotics Engineering 
courses sets the way for those who desire to design and 
manufacture robots for the many fields of this relatively new 
science. As they state, "The robotics revolution is underway, 
and a new breed of engineers is needed to face the 
challenges that this exciting field represents, WPI, the leader 
in project based education, continues its pioneering tradition 
by developing the nation's first Bachelor's degree program 
in Robotics Engineering. In addition, WPI also offers a 




FIGURE 2. The 2008 MIT ME 2.007 competition. 

Master's and Ph.D. in Robotics Engineering, with research in 
sensing, control, manipulation, learning, interaction, and 
medicine." 

WPI Robotics Team Took First 
Place in 2009 NASA Competition 

In the fall of 2009, the WPI sponsored robotics team 
took home first place in NASA's 2009 Regolith Excavation 
Challenge at the NASA Ames Research Center in Mountain 
View, CA. The challenge was to develop and demonstrate a 
robotic device that could dig up simulated moon dust/soil 
and deposit at least 1 50 kg of the material in a bin in 30 
minutes or less. There were three prizes: $500,000 for first 
(WPI); $150,000 for second; and $100,000 for third. The 
WPI team, headed by Paul Ventimiglia — a WPI robotics 
engineering major, beat 22 other teams by collecting and 
depositing 439 kg of regolith in the collection bin. 

Moonraker 2.0 shown in Figure 3 was built by 
Ventimiglia's team - Paul's Robotics - that also consisted of 



FIGURE 3. WPI 
NASA robot. 




SERVO 06.2011 77 



New Approaches In Robotics Education 



www.servomagazine.com/index.php7/magazine/article/june2011 ThenNow 




FIGURE 4. Hero 2000. 

WPI faculty, staff, sti 
and alumni, and was 
of NASA's Centennia 
Challenges Program 1 
was formed to help i 
innovative solutions t 
technical challenges i 
the aerospace indust 

Moon raker 
features a 
series of 
scoops that 
continually 
rotate to collect 
the lunar soil. Once 
the robot's bin is fu 
the team remotely 
navigates it to the 
collection bin and deposits 

the regolith by raising the collector arm. NASA specifies 
that the competing robots must be battery 
operated, weigh less than 80 kg, and fit within a * 

1 3 meter cylinder, NASA further specifies that W^ 

the robots must also employ only 
technology that could be used on the 
moon. Considering that the lunar soil 
is really the only natural resource 
available to future lunar pioneers, the 
use of this material is necessary to 
produce building materials, air, and 
water 

Teaching Materials for 
Robotics Classes 

About four years ago, I discussed the Heath Hero 
1 and Hero 2000 robots shown in Figure 4 and 
associated courses. In the '80s, 
courses such as these were 
about the only ^^ ^ * 

way a 
person 
could gain 



knowledge about this brand new field as there were 
virtually no robotics courses in higher lever institutions. 
Many community colleges eagerly used these robots as 
teaching aids as the core of electronics classes. The 
Heathkit Robotics and Industrial Electronics course was 
pretty thorough. In fact, I still have the manuals. Even 
though most preferred the arm on the mobile base, 
Heath sold an arm trainer (shown in Figure 5) that 
advanced classes could use for teaching basic industrial 
arm kinematics. There were a few other educational 
robots available in those days, such as the Microbot 
Teachmover shown in Figure 6. 

Robotics Education for Home 



and Classroom Study 




FIGURE 5, Hero 2000 

arm trainer. (Photo 

courtesy of theoldrohots.com ) 



Compared with the '80s, today's assortment of 
classroom materials for teachers of robotics at all levels 
is almost unlimited. Most of the educational 
materials currently available consist of complete 
mobile robots or mobile bases that students can 
adapt with sensor arrays, arms, or other 
devices. Costs for instructional materials can 
be less than $10 to hundreds of 
dollars per student. Several 
years ago when I lived on 
Orcas Island off the 
coast of 

Washington State, I 
saw some robot kits 
made by McGraw 
Hill at a discount 
bookseller for less 
than $10 that were 
originally $59.95 
each. The robots 
were based on the 
Microchip 
PIC16C505 
microcontroller (Figure 7). I 
ordered a couple dozen of these 
"Build Your Own Robot Kits" to teach a robotics class. It 
really doesn't take much to help a student realize that 
engineering, science, and robotics might lead to a rewarding 
career. 

There are dozens of quality robotics courses that are 
applicable to both home study and the classroom. Some use 
a mobile base as I mentioned earlier, or have a student build 
a series of different robots ranging from cute dogs to multi- 
legged walkers to humanoids. Multi-legged or humanoid 
robots are generally expensive due to the number of servos 
required to drive each degree of freedom or axis, and can 
cost well over $1,000. One of the most available robotics 
study series is the Parallax BoeBot kits (I covered these last 
month). The BoeBot shown in Figure 8 is a mobile robot 
system starting at about $150 and is based on the popular 
BASIC Stamp series of microcontrollers and the Board of 




FIGURE 6, Microbot Teachmover. 



78 SERVO 06.2011 



New Approaches To Robotics Education 



Education experimenter's board. These kits have found their 
way into homes, as well as classrooms around the world. 
Parallax has many kits and variations available for educators. 
The other tour de force in robotics education (and one 

of the first educational robot kit manufacturers) is the series 
of LEGO kits, The LEGO Mindstorms NXT 2.0 is the latest kit 
(shown in Figure 9) that features the powerful NXT 
microprocessor brick used with all their robots. This brick 
features a 32-bit processor with a large matrix display and 
four input and three output ports with Bluetooth and USB 
communications. The software has been greatly improved 
and the three servos, and two touch, ultrasonic distancing, 
and a color sensor complement the instruction manual to 
allow for classroom instruction, as well as a student learning 
on their own. 

The Korean company, Robotis, is also a player in the US 
educational field with a series of robotic 
kits based on their Dynamixel 

actuators — the most popular of 
which is the AX-12. These 

rotary actuators are 
similar to the many 
types of model 
aircraft servos 
that have 




FIGURES. 

Parallax 
BoeBot 




been used 
for years, but 
only in 
appearance. These 
smart actuators can be 
daisy-chained as shown in 
Figure 10, and rely only on a single 
serial address bus, power, and ground for any 
number of servos. The uniqueness of these 
actuators allows educators and students to 
use them in many configurations. Robotis' 
educational line begins with the OLLO 
Explorer kits for younger children then 
moves up to the many variations of the 
Bioloid kits and the more advanced 
Darwin-OP Open Platform Humanoid 
Project. 

Another kit is the Robotech Robodesigner 
Educational Robot Kit out of Japan. The basic two-level 
robot (shown in Figure 11) is available for $189.95, 
and offers endless robot configurations for classroom 
and individual study. This programmable robot kit is 
ideally suited for educational instruction for middle 
schools through university level classes, All basic parts 
are included in the kit. As Robotech states, "The 
RDS-X01 comes highly recommended by the Robot 
P.E.T.S. team due to its endless configuration options, 
sensors with line tracking capabilities, user friendly 
drag and drop programming interface, and optional 



teacher's manual/' 

STEM Education Coalition 

STEM is the latest acronym in today's educational 
sector. Standing for Science, Technology, Engineering, and 
Mathematics, the STEM Education Coalition works to 
support STEM programs for teachers and students at the US 
Department of Education, the National Science Foundation, 
and other agencies that offer STEM related programs. The 
US has managed to slip behind many other countries in the 
world with the number of students graduating in the fields 
of science and math. 



FIRST — For Inspiration and 
Recognition of Science and 
Technology 

My visit to the Autodesk 
Oregon Regional FIRST Robotics 
Competition in Portland was 
everything that I expected and 
more. Just as in Woodie 

Flowers' competitions at MIT, 
there were the cheers, the 
foot stomping, and hundreds 
of excited and very talented 
kids with some amazing robots. In this 
case, the Portland Rose Quarter was 
packed with grandstands full of 
supporters and a separate floor for 
the various team's 'pits' that exhibited 
the same energy and 
excitement as the 
competition arena. As 
someone I have long 
admired, inventor Dean 
Kamen's vision for FIRST was 
clearly evident in the several thousand 

SERVO 06.2011 79 




FIGURE 9. LEGO 
Mindstorms NXT 
2.0 robot. 



New Approaches In Robotics Education 



FIGURE 10. Dynamixel serial servo diagram. 
Instruction PackeUID-N^- 



Daity chain Link 




Status Display LED 

students, mentors, advisors, sponsors, and spectators. 
Woodie Flowers' spirit was also there, as he was the co- 
founder of the FIRST idea with Dean. I met many mothers 
who gladly called themselves Yobo moms' 
instead of 'soccer moms.' There were 
cheerleaders encouraging each team 
before their competition; flags were 
waving, banners were held high, and 
crowds clapped loudly as their team's 
results appeared on the scoreboard, 
I won't go into detail about the 
individual robot's construction, the 
contest's rules or scoring, but I'll 
mention that every year's event is 
different. There was an autonomous 
period in the "logo motion" competition 
where the robots hung yellow 'ubertubes' 
on hooks for initial scores, then later there 
was scoring for hanging red, white, and 
blue FIRST image tubes by remote 
control. Finally, there was the release of 
tiny minibots from each large robot to race up pipes in the 




FIGURE 11. Robotech robot. 



arena. FIRST is the largest robot competition in 
the nation, and is open to all high school age 
students. Figure 12 shows the FIRST Team #847 
PHRED in their pit making final preparations for 
competition. Typical of many of the teams, Team 
#847 is composed of 26 students that include 10 
girls, There are 10 mentors for the team and 20 
sponsors — that's 56 people working hard and 
having a lot of fun teaching and learning. Figure 
13 is a scene from the competition in Portland. 

Closing Thoughts 



In closing, t would like to emphasize that it is 
volunteerism that makes contests such as FIRST, 
BEST, and so many equally great robot contests to be 
thriving beds of inspiration for kids across the country. 
Sponsors range from JC Penny to Boeing to Autodesk and 
Mentor Graphics, as this takes a large financial worry off 
of budding teams. Education in robotics takes 
more than teachers. It takes funding of 
schools for the specialized materials 
needed for the classes. It takes parents 
who care and volunteer. It takes members of 
robotics groups such as the Seattle Robotics 
Society, who — along with a friend of mine, 
Kevin Ross — sent a team of volunteers 
down to Portland for this event. 

Be a mentor, a judge in a contest, a 
supplier of materials for a needy school's 
classes, or, most of all, be a robotics 
education supporter. If you're interested in 
robotics engineering yourself, use a search 
engine to discover the many colleges that 
teach variations of science or join a FIRST 
team in your area. Learning about robotics 
is the new wave I SV 



v\;^ cA 




FIGURE 12. Team #847 PHRED gets ready in the pits. 
80 SERVO 06.2011 



FIGURE 13. Portland FIRST 2011 competition. 




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